id
string
problem
string
answer
string
answer_type
string
category
string
difficulty
string
eval_score
int64
similar_problems
list
null
If we want to take the derivative $d/dx$ of $\int_{0}^{1} x^2dx$, what will the answer be? Does that mean to take $g(x) = \int_{0}^{1}x^2dx$ and find $g'(x)$? If so, we have $g(t) = \int_{0}^{1}t^2dx = t^2$ and therefore the derivative $d/dx$ of $\int_{0}^{1} x^2dx$ is $2x?$ What needs to be done first, calculate the i...
0
null
null
null
null
null
null
Find the work done by the force field F on a particle moving along the given path. F(x,y)=xi+8yj C:x=t, y=t^3 from (0,0) to (5,125)
None
null
null
null
null
null
null
What is the p-value for {eq}H_{0}: \mu =22{/eq} against {eq}H_{s}: \mu <22{/eq} if the sample statistics include {eq}\bar{x} = 18.2, s=9, n=36{/eq}?
None
null
null
null
null
null
null
The sales staff at ABC Corporation were overestimating sales revenues during the year. As a result of this overestimation, the firm might be paying its sales staff: a. a real wage that is higher than it should be. b. a real wage that is lower than it should be. c. a nominal wage that is higher than it should be. d....
None
null
null
null
null
null
null
Monopolistic competition is a: a) market structure characterized by the co-existence of many firms, producing close substitutes that are differentiated according to consumers. b) market structure characterized by the co-existence of many firms, producing perfect substitutes. c) market structure in which there is onl...
None
null
null
null
null
null
null
Find the Riemann sum for f(x) = x^2 + 2x over the interval [0, 4] , where x0 = 0, x1 = 1, x2 = 2, x3 = 3, and x4 = 4, and where c1 = 1, c2 = 2, c3 = 3, and c4 = 4.
None
null
null
null
null
null
null
While hiring a new worker, a firm will pay a higher wage than the prevailing market rate if: a. the labor market is less competitive b. the supply of workers is very high. c. the market demand for the new worker is low. d. the expected marginal revenue is positive.
d
null
null
null
null
null
null
Suppose the interest rate is 5.9%. How much do you have to invest today to have $2,000 in five years?
None
null
null
null
null
null
null
Which of the following is not correct? A. When goods are shipped FOB shipping point, the buyer should include freight-in costs in the cost of the inventory. B. The term perpetual inventory system refers to the fact that the inventory is recorded continuously. C. The perpetual inventory system requires a physical cou...
None
null
null
null
null
null
null
Determine whether the sequence converges or diverges. a_n = \frac{\sqrt{n^3 + 2n}}{\sqrt{2n^3 + 4}}
None
null
null
null
null
null
null
Suppose there are 1000 railroad ties per mile of track. On a certain railroad line, the probability that any tie is bad is 0.1. The appropriate theoretical distribution to estimate the probability of 20 or more bad ties in a quarter mile is: a. the binomial. b. the Poisson. c. the hypergeometric. d. the discrete un...
None
null
null
null
null
null
null
A professional baseball player makes $3.2 million in a year. What is his marginal tax rate on this income? Select the correct choice below and fill in the answer box to complete your choice. (Use a comma to separate answers.) A. The marginal tax rate is a(n) _____% rate. B. The marginal tax rate is 35%. C. The margi...
None
null
null
null
null
null
null
The impact of an exposure on a population does not depend upon a) the strength of the association between exposure and disease b) the prevalence of the exposure c) the case fatality rate d) the overall incidence rate of disease in the population
c
null
null
null
null
null
null
The inflation rate in an economy is estimated to be 3.0% for this year. The nominal GDP grew by 4.0% and the real GDP grew by 2.0%. Based on this information, we can conclude that: a. this year's inflation rate will be -1.0%. b. next year's inflation rate will be -1.0%. c. the unemployment rate will be greater than ...
None
null
null
null
null
null
null
Let $N_{24}$ denote the number of Sylow 2-subgroups in $S_{24}$. Find the remainder when $N_{24}$ is divided by 2011.
None
null
null
null
null
null
null
The face value of a government bond is $1,000, the coupon rate is 4%, and the bond matures in 10 years. It sells at a price of $1,035.72. What is the internal rate of return (IRR) of this bond? If you buy this bond, what will be your total return if the market interest rate on this debt remains the same over the next 1...
None
null
null
null
null
null
null
Which of the following is false? A. If the marginal revenue product of labor equals $100 and the marginal revenue product of capital is $200, then, if the wage rate is $50 and the rental rate of capital is $40, the firm can increase profits by hiring more capital and less labor. B. If the firm pays its employees more...
None
null
null
null
null
null
null
Why does the formula for the arithmetic mean (X) for a frequency distribution, which is X = (summation) fX / (summation) f, give the same result as X = (summation) X / N?
None
null
null
null
null
null
null
Let $V$ be a finite dimensional vector space over a field $F$ of dimension $n$. What is the minimum number of subspaces of $V$ such that fixing their images determine a unique vector space isomorphism $\varphi$ from $V$ to $V$?
n
null
null
null
null
null
null
Given an investment cost of $100,000 and an EAC of $20,000. What is the economic life? a. 7.27 years b. 6.64 years c. 5.00 years d. 10.00 years
None
null
null
null
null
null
null
Use the Ratio Test to find the values of {eq}x {/eq} for which the following series converges: {eq}\displaystyle \sum_{k=1}^{\infty} \frac{3^{k} x^{k}}{k^{2}} {/eq}.
None
null
null
null
null
null
null
The value of the firm's total product when the firm employs five units of labor, given the table below, is: TP MP_L 1 20 20 2 35 15 3 47 12 4 56 9 5 62 6 6 66 4 7 ...
None
null
null
null
null
null
null
How do you find the limit of #(sqrt(x+6)-x)/(x^3-3x^2)# as #x->-oo#?
None
null
null
null
null
null
null
Find the limit: {eq}\lim_{x \rightarrow 0} \frac{1}{x^2} - \frac{1}{\sin^2 x}{/eq}
None
null
null
null
null
null
null
In the Gaussian integers ring $\mathbb{Z}[i]$, how do I find the greatest common divisor of $16+7i$ and $10-5i$ using the Euclidean algorithm, given that the norm of the remainder increases with each step when using the Euclidean norm $N(a+bi) = a^2+b^2$?
$1 + 2i$
null
null
null
null
null
null
Fabian Company currently makes and sells a product for $30 per unit with variable costs of $20 per unit. Fixed overhead is $200,000. Fabian receives a special order for 10,000 units. Variable costs would be $25 per unit and fixed overhead would be $100,000. Fabian has the capacity to make 40,000 units per period. Assum...
None
null
null
null
null
null
null
I have a deck of cards, with four suits (13 cards in each suit). I keep taking out pairs of cards. If they are both red, I get one dollar. If they are both black, I lose one dollar. If one red and one black, I put them back. What is the expected value of this game?
None
null
null
null
null
null
null
Assume that Callaghan Motors' stock price is currently $50. In one year, the price will either fall to $30 or rise to $70. The risk-free rate is 10%. The price of a call option on Callaghan Motors' stock with an exercise price of $40 and a maturity of 1 year is _____.
None
null
null
null
null
null
null
Use a double integral to find the volume of the solid below z = y + 4 and above the region bounded by y = x^2 and y = 4.
None
null
null
null
null
null
null
Computer Corporation has an Accounts Payable balance at the end of 2015 of $600,000. At the end of 2016, the balance is $550,000. The total purchases on account during 2016 is $6.7 million. What is the cash disbursement for the purchase of merchandise in 2016?
None
null
null
null
null
null
null
Suppose that there is a stock with an expected of 12.5% and a volatility of 20%. The risk-free rate is 3% and you form a portfolio between the risk-free rate and the stock. What is the expected return on a portfolio which has a volatility of 15%?
10.125%
null
null
null
null
null
null
Solve the initial value problem {eq}y'' + y'+3y = \cos 2t, \ y(0)=0,\ y'(0)=1{/eq}
None
null
null
null
null
null
null
How to show that $(1+r)^t=\sum_{n=0}^{t} r^n$ with $t \in \mathbb{N}$ and $r \in \mathbb{R}$?
None
null
null
null
null
null
null
Pigeon Inc. is currently considering an eight-year project that has an initial outlay or cost of $80,000. The future cash inflows from its project for years 1 through 8 are the same at $30,000. Pigeon has a discount rate of 13%. Because of concerns about funds being short to finance all good projects, Pigeon wants to c...
None
null
null
null
null
null
null
A company is considering a project that will cost $775,000. The project will generate positive cash flows over the next four years in the amounts of $425,000 in year one, $300,000 in year two, $150,000 in year three, and $75,000 in year four. The required rate of return is 7%. The IRR of the project is: A. 4.23% B. 2...
None
null
null
null
null
null
null
Lehner Corporation is being liquidated. The corporation has $50,000 of cash in its checking account, $15,000 of fully depreciated equipment that will be sold for $9,000, and accounts receivable with a fair value of $13,000. Credit customers pay their accounts in 3 months. The corporation also has $8,000 in notes payabl...
None
null
null
null
null
null
null
A sample of 0.25 moles of an ideal gas expands from 72 milliliters to 10 liters. If the gas expands adiabatically against a constant pressure of 760 Torr, calculate the net heat transferred into the system.
0
null
null
null
null
null
null
What benefit does converting sales and profits to constant dollars in times of inflation offer when analyzing a case? A) It is helpful in predicting the future potential of the organization. B) It contributes to determining the risk factors when computing the Z value. C) It shows the true performance of the corporat...
None
null
null
null
null
null
null
When economic profits are negative, accounting profits: a. will be negative b. will equal zero c. must be positive d. could be positive, negative, or zero
None
null
null
null
null
null
null
Which of the following is true regarding the Capital Gain/Distribution rule? a. The return on capital stock is taxed at the highest marginal tax rate. b. Ordinary dividends and capital gain distributions are taxed at the same rate. c. Both ordinary dividends and capital gain distributions are taxed at the long-term ...
None
null
null
null
null
null
null
Laredo Co. had a $250,000 balance in its inventory account on December 31, 2015. The physical inventory indicated that $230,000 was actually on hand. Journalize the adjustment for inventory on December 31, 2015.
None
null
null
null
null
null
null
When bonds are sold at a discount, if the annual straight-line amortization amount is compared to the annual effective interest amortization amount over the life of the bond issue, the annual amount of the straight-line amortization of discount is: A. Hight than the effective interest amount every year. B. Hight than...
None
null
null
null
null
null
null
Find the Jacobian {eq}\displaystyle \frac{\partial (x,y,z)}{\partial (u,v,w)} {/eq} using the given equations: {eq}x = - 5u - 4 \ , \ \ y = 3v - 3 \ , \ \ z = - 4w + 4{/eq}
60
null
null
null
null
null
null
_____ is the study of how average prices are determined in different markets and industries. a. Equilibrium economics b. New classical economics c. Behavioral economics d. New institutional economics e. Monopolistic competition economics
None
null
null
null
null
null
null
Which of the following is false? a. Accounts receivable less bad debts is equal to net realizable value. b. The allowance method of accounting for bad debts is not compatible with the conservatism constraint. c. Under the allowance method, bad debts are recorded as an adjusting entry at the end of the period. d. Th...
None
null
null
null
null
null
null
What is the marginal cost of capital for a firm? a. the lowest cost source of long-term financing. b. the cost at which the firm can raise an additional dollar of new capital. c. the cost of the last dollar of capital. d. the average cost of all of the firm's outstanding long-term debt and equity.
None
null
null
null
null
null
null
How do I evaluate the sum $$\sum_{n=1}^{\infty} \frac{\cos(n \pi)}{n}$$ and can you please show me how to obtain the Fourier series of $f(t)=t$ over the interval $-\pi \le t \le \pi$?
None
null
null
null
null
null
null
Uchida’s optical imaging research showed that as the length of the carbon chain increases, the area of activation is _____. a. ​randomly distributed across the glomeruli b. ​located more to the right c. ​more centrally located d. ​located more to the left
None
null
null
null
null
null
null
A study is going to be conducted in which a mean of a lifetime of batteries produced by a certain method will be estimated using a 90% confidence interval. The estimate needs to be within $\pm 2$ hours of the actual population mean. The population standard deviation is estimated to be around 25. The necessary sample si...
423
null
null
null
null
null
null
The random variable X has a binomial distribution with n = 100 and p = 0.1. Which of the following is true about the random variable X? a) It has the same expected value as the number of heads in 100 tosses of a coin. b) It has a smaller standard deviation than the number of heads in 100 tosses of a coin. c) It has ...
None
null
null
null
null
null
null
Currently, a firm's capital structure is 30 percent debt and 70 percent equity. The tax rate is 21 percent, and the cost of debt capital is 6 percent. The risk-free rate is 4.5 percent and the risk premium on the market portfolio is 7.2 percent. The beta of the company's stock is 2. The firm's capital budget of $80 mil...
None
null
null
null
null
null
null
Suppose the Fed buys government bonds with the excess reserves it has accumulated. Assume that the interest rates are equal to 0%. The demand for money with respect to interest rates _____ and the demand for money with respect to income _____. A) is downward sloping; is upward sloping B) is upward sloping; is upward ...
None
null
null
null
null
null
null
Which view of perception suggests that stimuli may be richly informative and perceptual processes may be very complex? a. Intelligent topographical. b. Synthesis of bottom-up and top-down. c. Top-down. d. Bottom-up.
None
null
null
null
null
null
null
Which of the following are potential advantages of the corporate form of organization? I. Separation of ownership and management II. Ease of ownership transfer III. Limited liability for all owners IV. Ability to raise large sums of equity capital A. I, II, and III only B. I and II only C. III and IV only D. I,...
None
null
null
null
null
null
null
Determine the sample size needed to construct a 95% confidence interval with a margin of error equal to 0.005 ounces. Assume the standard deviation for the potato chip filling process is 0.04 ounces.
246
null
null
null
null
null
null
Suppose the information in the following table is for a simple economy that produces only the following four goods: 2009 Statistics 2014 Statistics 2015 Statistics Product Quantity Price Quantity Price Quantity Price Shoes 110 $55....
None
null
null
null
null
null
null
Use the cylindrical coordinate to evaluate {eq}\int \int \int_{E}x^3\,dV{/eq}, where E is enclosed by the planes z = 0 and z = x + 6 and by the cylinders {eq}x^2 + y^2 = 1{/eq} and {eq}x^2 + y^2 = 16{/eq}.
None
null
null
null
null
null
null
Consider the ring $R=\{f(x) \in \mathbb{Z}_5[x]: \text{deg}(f(x))\leq3\}$. Which of the following statements are correct? (A) The number of invertible elements in $R$ is $5^4-5^3$. (B) The number of ideals of $R$ is 15. (C) The number of maximal ideals of $R$ is 5. (D) The ring $R$ has exactly one non-zero zero div...
None
null
null
null
null
null
null
Gentle Gents, Inc. has 10,000 shares of common stock outstanding at a price of $88 a share. It also has 2,000 shares of preferred stock outstanding at a price of $62 a share. There are 400 shares of debt outstanding that have a total face value of $200,000 and a market value of $50,000. Preferred stock pays an annual d...
None
null
null
null
null
null
null
The table shows the units of a good produced and the total utility derived by a consumer from those units: Quantity Total Utility 0 0 1 12 2 22 3 31 4 37 5 40 Refer to the Table above. The marginal utility of the 5th unit equals: a. 16 units b. 9 units c. 1 unit d. 5 units e. 40 units
None
null
null
null
null
null
null
Southwest Physicians, a medical group practice, is just being formed. It will need $2 million of total assets to generate $3 million in revenues. Furthermore, the group expects to have a profit margin of 5 percent. The group is considering two financing alternatives. First, it can use all-equity financing by requiring ...
7.5%
null
null
null
null
null
null
You are considering investing in one of three mutual funds. All three of the funds have the same average return of 12%. Fund A has a standard deviation of 6% and a beta of 0.8. Fund B has a standard deviation of 5% and a beta of 1.3. Fund C has a standard deviation of 7% and a beta of 1.5. If you are a rational ri...
None
null
null
null
null
null
null
Acme Construction Company is considering investing in a new project that will cost $8 million. The company believes it can recoup the initial investment in 4 years through the net cash flows of $2,750,000 for the first year, $2,500,000 for the second year, $2,250,000 for the third year, and $2,000,000 for the fourth ye...
None
null
null
null
null
null
null
Which of the following types of firms are likely to have the least stable cost of capital? a. firms with large market power b. mature firms c. firms with stable cash flows d. firms that depend heavily on current R&D efforts e. small firms
None
null
null
null
null
null
null
How many terms of the Taylor series of f(x)=e^{x^3} centered at 0 would you need to compute to evaluate e^{0.6^3} accurate to 7 decimal places?
None
null
null
null
null
null
null
In macroeconomics, we analyze a. all of the following b. the overall performance of the economy as a whole c. arrangements through which specific products are exchanged d. influences on the decision making of particular households
None
null
null
null
null
null
null
You bought a semiannual interest rate cap on $8 million notional with K=3% (annually, rate quotes are almost always in annual terms). Today is one of the interest settlement dates and you realize that six months ago the (annual) LIBOR rate was 4%. What is your payoff?
$40,000.00
null
null
null
null
null
null
Find the limit: {eq}\lim_{x \to 0^+} ( \frac{1}{x^2} - \frac{1}{\sin x} ) {/eq}
None
null
null
null
null
null
null
Which of the following is NOT a source of money creation? A. Commercial banks B. The U.S. Treasury C. Financial markets D. The Federal Reserve
None
null
null
null
null
null
null
ArnoldKen began blogging about Apple products during his fourth year of medical school. Kim's website, MacRumors.com became so successful that he decides to give up his medical career and work full time on his Website despite nearly $200,000 he had invested in his education. In making his decision, Kim decided to ignor...
None
null
null
null
null
null
null
Find the word from the options that has the closest relationship to the given word. Benefit : Damage a. dispense : distribute b. remunerate : compensate c. jurisprudence : legislation d. cure : heal e. ameliorate : improve
None
null
null
null
null
null
null
When actual production exceeds the expected production due to an increase in sales, the: a. fixed manufacturing overhead budget variance is favorable b. fixed manufacturing overhead volume variance is unfavorable c. fixed manufacturing overhead budget variance is unfavorable d. fixed manufacturing overhead volume v...
None
null
null
null
null
null
null
Calculate the integral. Do not simplify the answer. {eq}\int \frac{\cos (\sqrt z+3)}{\sqrt z}dz{/eq}
2sin(sqrt(z)+3)+C
null
null
null
null
null
null
Find the tangent plane to the graph of f(x, y) = xy at the point P_0(1, 1).
None
null
null
null
null
null
null
Using the retail method, beginning inventory at cost is $65,000. Beginning inventory at retail is $90,000. Net purchases at cost are $180,000. Net purchases at retail are $290,000. Sales at retail are $310,000. The ending inventory at retail is: A) $230,000. B) $94,000. C) $110,000. D) $65,000.
None
null
null
null
null
null
null
What financial statement effect results from the purchase of equipment using short-term financing? a) increase in assets and liabilities b) increase in assets and stockholders' equity c) decrease in liabilities and stockholders' equity d) increase in assets, liabilities, and stockholders' equity e) decrease in ass...
None
null
null
null
null
null
null
You are considering an investment in Justus Shoes, Inc.'s stock. The company has paid a constant annual dividend of $3.60 per share over the past 10 years. This dividend policy is expected to continue for the foreseeable future. The market price of Justus' stock is $26.80 per share. Use the dividend growth model to cal...
None
null
null
null
null
null
null
Integrate the following directly and determine the probability that the density function of a random variable Y is given by {eq}f(y) = 3(1-y)^2{/eq} for 0 < y < 1, and the batch of a chemical can be sold because the percentage of impurities per batch is less than 40%.
None
null
null
null
null
null
null
Baker Corporation uses the weighted-average method in its process costing system. The Assembly Department started the month with 9,600 units in its beginning work in process inventory that were 90% complete with respect to conversion costs. An additional 97,000 units were transferred in from the prior department during...
105,100
null
null
null
null
null
null
Erickson Inc. is currently considering an eight-year project that has an initial outlay or cost of $75,000. The future cash inflows from its project for years 1 through 8 are the same at $25,000. Erickson has a discount rate of 14%. Because of concerns about funds being short to finance all good projects, Erickson want...
None
null
null
null
null
null
null
Determine whether the sequence {eq}\displaystyle a_n = (\ln(n))^{\frac{1}{n}} {/eq} converges or diverges.
None
null
null
null
null
null
null
Work-in-process: beginning balance, $42,000; completed and transferred out, $276,000; direct materials used, $67,000; conversion costs, $107,000. Calculate the cost of goods transferred out.
None
null
null
null
null
null
null
Under IFRS, which of the following statements is incorrect? a. Contingent liabilities must be accrued if the outcome of a future event is probable and the liability can be reasonably estimated. b. A company must accrue a loss on a lawsuit if it is virtually certain that a loss has been incurred and the amount of the ...
None
null
null
null
null
null
null
A light bulb manufacturing company wants to estimate, with 95% confidence, the proportion of defective light bulbs. The estimate must be accurate within 0.015 of the true proportion. What is the minimum sample size needed?
None
null
null
null
null
null
null
Use a triple integral to find the volume of a solid in the 1st octant whose roof is z=4-x^2, with boundaries in the xy-plane of y=x, y=x, and x=0. Draw the three-dimensional solid.
4
null
null
null
null
null
null
The retail price of a product is $38.20. The gross profit is 17.8% of retail, and the selling and administrative expenses are 12% of the selling price. The contribution margin is: A. 42.20% B. 62.2% C. 25.40% D. 50%
None
null
null
null
null
null
null
Which of the following is NOT a factor affecting the choice of capital structure? a. Taxation b. Management attitude c. Size and profit level of the company d. Cash flow generation from assets
None
null
null
null
null
null
null
Valley Company uses a job-order costing system and applies overhead to production on the basis of direct labor costs. On January 1, 2016, Job 50 was the only job in the process. The costs incurred prior to January 1 on this job were as follows: direct materials $10,000, direct labor $5,000, and manufacturing overhead $...
None
null
null
null
null
null
null
Calculate the future value of $10,000, given that the interest rate is 10% and the number of periods is 5.
None
null
null
null
null
null
null
How many solutions does the equation $x_1+x_2+x_3+x_4=10$ have, if $x_i\geq i$ for $i=1,2,3,4$?
None
null
null
null
null
null
null
Which of the following statements regarding the tangent line is false? a) the tangent line just touches total production curve b) the slope of the tangent line is equal to the slope of the TP curve at a specific point c) the tangent line is used to find the slope of the TP curve d) the tangent line cannot be used t...
d
null
null
null
null
null
null
Tri-Cities Trout Farm will pay an annual dividend of $0.27 a share next year with future dividends growing at 1.2 percent per year. If the market rate of return on this stock is 7.4 percent, how much are you willing to pay for one share of this stock today?
None
null
null
null
null
null
null
Jesters-R-Us Inc. is a publically traded company that has assets on its balance sheet of $129.82 million and liabilities of $79.8 million. The firm also has 3.6 million common shares that are currently trading for $20.18 per share. a) Estimate the firm's market-to-book ratio. (Round to two decimal places.) Market...
None
null
null
null
null
null
null
Mannarini Company reports the following information: Net Income $360,000 Depreciation expense 34,000 Gain on disposal of equipment 26,000 Increase in accounts receivable 32,000 Decrease in accounts payable 40,000 Cash paid to suppliers 144,000 ...
None
null
null
null
null
null
null
For annuity with $i = 15$%, determine the present value at the beginning of the annuity of $100 per month for 2 years.
None
null
null
null
null
null
null
Where is the center of mass of a thin triangular plate in the plane with vertices at (0, 0), (2, 0) and (2, 1), assuming the mass density ρ = 1?
None
null
null
null
null
null
null
Which of the following leads to an rightward shift in the short-run Phillips curve? I. a reduction in inflationary expectations. II. an increase in the natural rate of unemployment. III. an increase in the velocity of circulation A: I only B: II only C: I and II D: I and III
B
null
null
null
null
null
null
The manager of the Really Cheap Beer brewery has calculated that daily demand for RCB's light beer, q cases of beer, and the price of a case, p are related by the equation p + 0.0006q = 12. He also knows that his daily marginal cost on a case of beer is C'(q) = 2 + 0.0013q dollars per case. In these problems, we will a...
None
null
null
null
null
null
null
If someone who earns $20,000 has a 36% probability of being sampled and someone who earns $100,000 has a 12% probability, what does this imply about the representativeness of the sample to the population? A. The sample is more likely to over-represent low-income individuals than the population. B. The sample is more ...
None
null
null
null
null
null
null
Let $M$ be a $3 \times 3$ matrix such that $\det (M)= 15$. Then what is the determinant of the matrix obtained by adding the second column to the first column and then subtracting the first column from the second column in $M$?
None
null
null
null
null
null