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A rectangular piece of paper with vertices $A B C D$ is being cut by a pair of scissors. The pair of scissors starts at vertex $A$, and then cuts along the angle bisector of $D A B$ until it reaches another edge of the paper. One of the two resulting pieces of paper has 4 times the area of the other piece. What is the ...
\frac{5}{2}
Without loss of generality, let $A B>A D$, and let $x=A D, y=A B$. Let the cut along the angle bisector of $\angle D A B$ meet $C D$ at $E$. Note that $A D E$ is a $45-45-90$ triangle, so $D E=A D=x$, and $E C=y-x$. Now, $[A D E]=\frac{x^{2}}{2}$, and $[A E C B]=x\left(y-\frac{x}{2}\right)=4[A D E]$. Equating and divid...
0.5
6,903.125
5,736.75
8,069.5
Six students sign up for three different intellectual competition events. How many different registration methods are there under the following conditions? (Not all six students must participate) (1) Each person participates in exactly one event, with no limit on the number of people per event; (2) Each event is limi...
216
0.0625
5,995.8125
1,971
6,264.133333
Find the product of $0.5$ and $0.8$.
0.4
0.625
579.5
729.3
329.833333
For the equation $6 x^{2}=(2 m-1) x+m+1$ with respect to $x$, there is a root $\alpha$ satisfying the inequality $-1988 \leqslant \alpha \leqslant 1988$, and making $\frac{3}{5} \alpha$ an integer. How many possible values are there for $m$?
2385
0.5
7,675.6875
7,159.375
8,192
A biased coin with the probability of landing heads as 1/3 is flipped 12 times. What is the probability of getting exactly 9 heads in the 12 flips?
\frac{1760}{531441}
0.875
4,656.375
4,151.285714
8,192
Determine the number of ways to select 4 representatives from a group of 5 male students and 4 female students to participate in an activity, ensuring that there are at least two males and at least one female among the representatives.
100
0.1875
7,039.0625
6,631.666667
7,133.076923
Given $m \gt 0$, $n \gt 0$, and $m+2n=1$, find the minimum value of $\frac{(m+1)(n+1)}{mn}$.
8+4\sqrt{3}
0.4375
7,915.0625
7,559
8,192
In the geometric sequence $\{a_n\}$, if $a_2a_5= -\frac{3}{4}$ and $a_2+a_3+a_4+a_5= \frac{5}{4}$, calculate $\frac{1}{a_2}+ \frac{1}{a_3}+ \frac{1}{a_4}+ \frac{1}{a_5}$.
-\frac{5}{3}
0.25
7,528.5
5,538
8,192
The Ivanov family consists of three people: a father, a mother, and a daughter. Today, on the daughter's birthday, the mother calculated the sum of the ages of all family members and got 74 years. It is known that 10 years ago, the total age of the Ivanov family members was 47 years. How old is the mother now if she ga...
33
0
8,192
-1
8,192
The ticket price for a cinema is: 6 yuan per individual ticket, 40 yuan for a group ticket for every 10 people, and students enjoy a 10% discount. A school with 1258 students plans to watch a movie (teachers get in for free). The school should pay the cinema at least ____ yuan.
4536
0.125
7,030.5
3,291.5
7,564.642857
Consider a circular cone with vertex $V$, and let $ABC$ be a triangle inscribed in the base of the cone, such that $AB$ is a diameter and $AC=BC$. Let $L$ be a point on $BV$ such that the volume of the cone is 4 times the volume of the tetrahedron $ABCL$. Find the value of $BL/LV$.
\frac{\pi}{4-\pi}
Let $R$ be the radius of the base, $H$ the height of the cone, $h$ the height of the pyramid and let $BL/LV=x/y$. Let [.] denote volume. Then [cone] $=\frac{1}{3} \pi R^{2} H$ and $[ABCL]=\frac{1}{3} \pi R^{2} h$ and $h=\frac{x}{x+y} H$. We are given that [cone] $=4[ABCL]$, so $x/y=\frac{\pi}{4-\pi}$.
0.75
6,249.875
5,602.5
8,192
Let the set \(M = \{1,2,\cdots, 1000\}\). For any non-empty subset \(X\) of \(M\), let \(\alpha_X\) denote the sum of the largest and smallest numbers in \(X\). Find the arithmetic mean of all such \(\alpha_X\).
1001
0.4375
7,111.6875
5,722.714286
8,192
Given an ant crawling inside an equilateral triangle with side length $4$, calculate the probability that the distance from the ant to all three vertices of the triangle is more than $1$.
1- \dfrac { \sqrt {3}\pi}{24}
0
5,259.125
-1
5,259.125
In a parlor game, the magician asks one of the participants to think of a three digit number $(abc)$ where $a$, $b$, and $c$ represent digits in base $10$ in the order indicated. The magician then asks this person to form the numbers $(acb)$, $(bca)$, $(bac)$, $(cab)$, and $(cba)$, to add these five numbers, and to rev...
358
Let $m$ be the number $100a+10b+c$. Observe that $3194+m=222(a+b+c)$ so \[m\equiv -3194\equiv -86\equiv 136\pmod{222}\] This reduces $m$ to one of $136, 358, 580, 802$. But also $a+b+c=\frac{3194+m}{222}>\frac{3194}{222}>14$ so $a+b+c\geq 15$. Of the four options, only $m = \boxed{358}$ satisfies this inequality.
0.25
7,767.125
6,492.5
8,192
Given points \(A(4,5)\), \(B(4,0)\) and \(C(0,5)\), compute the line integral of the second kind \(\int_{L}(4 x+8 y+5) d x+(9 x+8) d y\) where \(L:\) a) the line segment \(OA\); b) the broken line \(OCA\); c) the parabola \(y=k x^{2}\) passing through the points \(O\) and \(A\).
\frac{796}{3}
0.4375
6,533.8125
5,704.714286
7,178.666667
Given the function $f(x) = \sqrt{3}\sin x\cos x + \cos^2 x + a$. (1) Find the smallest positive period and the monotonically increasing interval of $f(x)$; (2) If the sum of the maximum and minimum values of $f(x)$ in the interval $[-\frac{\pi}{6}, \frac{\pi}{3}]$ is $1$, find the value of $a$.
a = -\frac{1}{4}
0.625
6,307.8125
6,156.5
6,560
There exist constants $c_1$ and $c_2$ such that \[c_1 \begin{pmatrix} 2 \\ 3 \end{pmatrix} + c_2 \begin{pmatrix} -2 \\ 5 \end{pmatrix} = \begin{pmatrix} -1 \\ 4 \end{pmatrix}.\]Enter the ordered pair $(c_1,c_2).$
\left( \frac{3}{16}, \frac{11}{16} \right)
1
2,570.75
2,570.75
-1
In the list where each integer $n$ appears $n$ times for $1 \leq n \leq 300$, find the median of the numbers.
212
0.8125
5,297.25
4,629.230769
8,192
A month with $31$ days has the same number of Mondays and Wednesdays. How many of the seven days of the week could be the first day of this month?
3
To solve this problem, we need to determine how many days of the week could be the first day of a month with 31 days such that the number of Mondays and Wednesdays in that month are equal. 1. **Understanding the Weekday Distribution:** A month with 31 days spans exactly 4 weeks and 3 extra days. This means that eac...
0.0625
8,145.9375
8,192
8,142.866667
Let $n$ be a positive integer. A pair of $n$-tuples \left(a_{1}, \ldots, a_{n}\right)$ and \left(b_{1}, \ldots, b_{n}\right)$ with integer entries is called an exquisite pair if $$\left|a_{1} b_{1}+\cdots+a_{n} b_{n}\right| \leq 1$$ Determine the maximum number of distinct $n$-tuples with integer entries such that any ...
n^{2}+n+1
The maximum is $n^{2}+n+1$. First, we construct an example with $n^{2}+n+1 n$-tuples, each two of them forming an exquisite pair. In the following list, $*$ represents any number of zeros as long as the total number of entries is $n$. ・ $(*)$ ・ $(*, 1, *)$ - $(*,-1, *)$ - $(*, 1, *, 1, *)$ - $(*, 1, *,-1, *)$ For examp...
0
8,192
-1
8,192
Let $z$ and $w$ be complex numbers such that $|z| = 1$ and $|w| = 3$. If $|z+w| = 2$, what is $ \left | \frac{1}{z} + \frac{1}{w} \right|$?
\frac{2}{3}
1
4,072.25
4,072.25
-1
$\frac{9}{7 \times 53} =$
$\frac{0.9}{0.7 \times 53}$
To solve the problem, we need to convert the fraction $\frac{9}{7 \times 53}$ into a form that matches one of the given options. We start by expressing the numbers in decimal form and then simplify the expression. 1. **Convert integers to decimals:** - The number 9 can be written as 0.9 multiplied by 10. - The n...
0
6,944.6875
-1
6,944.6875
A geometric sequence of positive integers has its first term as 5 and its fourth term as 480. What is the second term of the sequence?
20
0
8,192
-1
8,192
As $x$ ranges over all real numbers, find the range of \[f(x) = \sin^4 x + \cos ^2 x.\]Enter your answer using interval notation.
\left[ \frac{3}{4}, 1 \right]
1
4,230.3125
4,230.3125
-1
Determine the number of ways to arrange the letters of the word "PERCEPTION".
907200
0.0625
1,855.375
2,488
1,813.2
**Compute the sum of all four-digit numbers where every digit is distinct and then find the remainder when this sum is divided by 1000.**
720
0
6,919.1875
-1
6,919.1875
The steamboat "Rarity" travels for three hours at a constant speed after leaving the city, then drifts with the current for an hour, then travels for three hours at the same speed, and so on. If the steamboat starts its journey in city A and goes to city B, it takes it 10 hours. If it starts in city B and goes to city ...
60
0
7,812.5
-1
7,812.5
Let $A, B, C, D, E, F$ be 6 points on a circle in that order. Let $X$ be the intersection of $AD$ and $BE$, $Y$ is the intersection of $AD$ and $CF$, and $Z$ is the intersection of $CF$ and $BE$. $X$ lies on segments $BZ$ and $AY$ and $Y$ lies on segment $CZ$. Given that $AX=3, BX=2, CY=4, DY=10, EZ=16$, and $FZ=12$, f...
\frac{77}{6}
Let $XY=z, YZ=x$, and $ZX=y$. By Power of a Point, we have that $3(z+10)=2(y+16), 4(x+12)=10(z+3), \text{ and } 12(x+4)=16(y+2)$. Solving this system gives $XY=\frac{11}{3}$ and $YZ=\frac{14}{3}$ and $ZX=\frac{9}{2}$. Therefore, the answer is $XY+YZ+ZX=\frac{77}{6}$.
0
8,192
-1
8,192
Point $M(4,4)$ is the midpoint of $\overline{AB}$. If point $A$ has coordinates $(8,4)$, what is the sum of the coordinates of point $B$?
4
1
1,308.625
1,308.625
-1
In the diagram, $\triangle ABE$, $\triangle BCE$ and $\triangle CDE$ are right-angled, with $\angle AEB=\angle BEC = \angle CED = 45^\circ$, and $AE=28$. Find the length of $CE$, given that $CE$ forms the diagonal of a square $CDEF$.
28
0
7,738
-1
7,738
To prepare for her half-marathon, Mary ran a total of $2847_9$ miles. How many miles (in base ten) did Mary run?
2149
1
3,325.3125
3,325.3125
-1
The state income tax where Kristin lives is levied at the rate of $p\%$ of the first $\$28000$ of annual income plus $(p + 2)\%$ of any amount above $\$28000$. Kristin noticed that the state income tax she paid amounted to $(p + 0.25)\%$ of her annual income. What was her annual income?
32000
Let $A$ represent Kristin's annual income and $T$ represent the total income tax she paid. The tax rate is $p\%$ for the first $\$28000$ and $(p+2)\%$ for any amount above $\$28000$. We are given that the total tax $T$ is also $(p+0.25)\%$ of her annual income $A$. 1. **Express the total tax $T$ in terms of $p$ and $A...
0.875
4,253
3,690.285714
8,192
In the arithmetic sequence $\{a_n\}$, $S_{10} = 4$, $S_{20} = 20$. What is $S_{30}$?
48
0.9375
4,573.625
4,332.4
8,192
If $A,B$ and $C$ are non-zero distinct digits in base $6$ such that $\overline{ABC}_6 + \overline{BCA}_6+ \overline{CAB}_6 = \overline{AAA0}_6$, find $B+C$ in base $6$.
5
0.875
4,476.5
3,945.714286
8,192
For a four-digit natural number $M$, if the digit in the thousands place is $6$ more than the digit in the units place, and the digit in the hundreds place is $2$ more than the digit in the tens place, then $M$ is called a "naive number." For example, the four-digit number $7311$ is a "naive number" because $7-1=6$ and...
9313
0.5
7,083.25
6,133.75
8,032.75
How many positive integers less than $1000$ are either a perfect cube or a perfect square?
38
0
3,763.5625
-1
3,763.5625
Estimate $A$, the number of times an 8-digit number appears in Pascal's triangle. An estimate of $E$ earns $\max (0,\lfloor 20-|A-E| / 200\rfloor)$ points.
180020660
We can obtain a good estimate by only counting terms of the form $\binom{a}{1},\binom{a}{2},\binom{a}{a-1}$, and $\binom{a}{a-2}$. The last two cases are symmetric to the first two, so we will only consider the first two and multiply by 2 at the end. Since $\binom{a}{1}=a$, there are 90000000 values of $a$ for which $\...
0
8,192
-1
8,192
Consider the ellipse $\frac{x^2}{16} + \frac{y^2}{12} = 1$ whose left and right intersection points are $F_1$ and $F_2$, respectively. Let point $P$ be on the ellipse and satisfy $\vec{PF_1} \cdot \vec{PF_2} = 9$. Find the value of $|\vec{PF_1}| \cdot |\vec{PF_2}|$.
15
0.875
4,319.3125
3,766.071429
8,192
The sequence $(x_n)$ is determined by the conditions: $x_0=1992,x_n=-\frac{1992}{n} \cdot \sum_{k=0}^{n-1} x_k$ for $n \geq 1$ . Find $\sum_{n=0}^{1992} 2^nx_n$ .
1992
0
8,192
-1
8,192
Carl decided to fence his rectangular flowerbed using 24 fence posts, including one on each corner. He placed the remaining posts spaced exactly 3 yards apart along the perimeter of the bed. The bed’s longer side has three times as many posts compared to the shorter side, including the corner posts. Calculate the area ...
144
0.3125
5,732
4,446.8
6,316.181818
What is the sum of the digits of all numbers from one to one billion?
40500000001
0
8,192
-1
8,192
Given that Mary is 30% older than Sally, and Sally is 50% younger than Danielle, and the sum of their ages is 45 years, determine Mary's age on her next birthday.
14
1
3,835.5625
3,835.5625
-1
Let $f(n)$ be the integer closest to $\sqrt[4]{n}.$ Find $\sum_{k=1}^{1995}\frac 1{f(k)}.$
400
0.1875
7,597.25
6,042.666667
7,956
In the Cartesian coordinate plane, the number of integer points (points where both the x-coordinate and y-coordinate are integers) that satisfy the system of inequalities \[ \begin{cases} y \leq 3x, \\ y \geq \frac{1}{3}x, \\ x + y \leq 100 \end{cases} \] is ___.
2551
0
8,192
-1
8,192
Given the ellipse $x^{2}+4y^{2}=16$, and the line $AB$ passes through point $P(2,-1)$ and intersects the ellipse at points $A$ and $B$. If the slope of line $AB$ is $\frac{1}{2}$, then the value of $|AB|$ is ______.
2\sqrt{5}
0.9375
3,479.4375
3,165.266667
8,192
Given the ellipse $C$: $\frac{x^{2}}{a^{2}}+ \frac{y^{2}}{b^{2}}=1 (a > b > 0)$ passing through the point $E(\sqrt{3}, 1)$, with an eccentricity of $\frac{\sqrt{6}}{3}$, and $O$ as the coordinate origin. (I) Find the equation of the ellipse $C$; (II) If point $P$ is a moving point on the ellipse $C$, and the perpendicu...
\sqrt{6}
0.625
7,037.9375
6,504.8
7,926.5
Given that $\alpha$ is an acute angle, $\beta$ is an obtuse angle, $\cos\alpha=\frac{3}{5}$, $\sin\beta=\frac{5}{13}$, $(1)$ Find $\sin(\alpha - \beta)$ and $\cos(\alpha - \beta)$; $(2)$ Find the value of $\tan 2\alpha$.
-\frac{24}{7}
0.9375
3,802.3125
3,509.666667
8,192
A triangle has side lengths of $x,75,100$ where $x<75$ and altitudes of lengths $y,28,60$ where $y<28$ . What is the value of $x+y$ ? *2019 CCA Math Bonanza Team Round #2*
56
0.5625
7,331.75
6,662.666667
8,192
Mafia is a game where there are two sides: The village and the Mafia. Every night, the Mafia kills a person who is sided with the village. Every day, the village tries to hunt down the Mafia through communication, and at the end of every day, they vote on who they think the mafia are.**p6.** Patrick wants to play a gam...
319/512
0
8,192
-1
8,192
If $\lceil{\sqrt{x}}\rceil=20$, how many possible integer values of $x$ are there?
39
0.4375
4,260.5625
2,698.571429
5,475.444444
Let $P A B C$ be a tetrahedron such that $\angle A P B=\angle A P C=\angle B P C=90^{\circ}, \angle A B C=30^{\circ}$, and $A P^{2}$ equals the area of triangle $A B C$. Compute $\tan \angle A C B$.
8+5 \sqrt{3}
Observe that $$\begin{aligned} \frac{1}{2} \cdot A B \cdot A C \cdot \sin \angle B A C & =[A B C]=A P^{2} \\ & =\frac{1}{2}\left(A B^{2}+A C^{2}-B C^{2}\right) \\ & =A B \cdot A C \cdot \cos \angle B A C \end{aligned}$$ so $\tan \angle B A C=2$. Also, we have $\tan \angle A B C=\frac{1}{\sqrt{3}}$. Also, for any angles...
0.1875
8,059.0625
7,483
8,192
What is the least positive integer that is divisible by the primes 7, 11, and 13?
1001
1
1,042.9375
1,042.9375
-1
Each of the ten cards has a real number written on it. For every non-empty subset of these cards, the sum of all the numbers written on the cards in that subset is calculated. It is known that not all of the obtained sums turned out to be integers. What is the largest possible number of integer sums that could have res...
511
0
8,104.4375
-1
8,104.4375
**How many positive factors does 72 have, and what is their sum?**
195
0.375
1,106.4375
1,775.5
705
The three roots of the equation \[ax^3+bx^2+cx+d=0\]are $1,$ $2,$ and $3.$ Compute $\frac{c}{d}.$
-\frac{11}{6}
1
2,213.5625
2,213.5625
-1
The value of \(\frac{1}{1+\frac{1}{1+\frac{1}{2}}}\) can be expressed as a simplified fraction.
\frac{3}{5}
0.9375
2,245.8125
2,298.8
1,451
Find the flux of the vector field $$ \vec{a}=-x \vec{i}+2 y \vec{j}+z \vec{k} $$ through the portion of the plane $$ x+2 y+3 z=1 $$ located in the first octant (the normal forms an acute angle with the $OZ$ axis).
\frac{1}{18}
0.25
7,873.6875
7,652.5
7,947.416667
Let $p,$ $q,$ $r,$ $s$ be distinct real numbers such that the roots of $x^2 - 12px - 13q = 0$ are $r$ and $s,$ and the roots of $x^2 - 12rx - 13s = 0$ are $p$ and $q.$ Find the value of $p + q + r + s.$
1716
0
7,603.5625
-1
7,603.5625
A particle moves in a straight line inside a square of side 1. It is reflected from the sides, but absorbed by the four corners. It starts from an arbitrary point \( P \) inside the square. Let \( c(k) \) be the number of possible starting directions from which it reaches a corner after traveling a distance \( k \) or ...
\pi
0.4375
7,356.5
6,282.285714
8,192
Piravena must make a trip from $A$ to $B,$ then from $B$ to $C,$ then from $C$ to $A.$ Each of these three parts of the trip is made entirely by bus or entirely by airplane. The cities form a right-angled triangle as shown, with $C$ a distance of $3000\text{ km}$ from $A$ and with $B$ a distance of $3250\text{ km}$ fro...
\$425
0.9375
3,395.75
3,076
8,192
Let \( ABC \) be any triangle. Let \( D \) and \( E \) be points on \( AB \) and \( BC \) respectively such that \( AD = 7DB \) and \( BE = 10EC \). Assume that \( AE \) and \( CD \) meet at a point \( F \). Determine \( \lfloor k \rfloor \), where \( k \) is the real number such that \( AF = k \times FE \).
77
0.4375
6,829.125
5,076.857143
8,192
Let $q(x) = 2x^6 - 3x^4 + Dx^2 + 6$ be a polynomial. When $q(x)$ is divided by $x - 2$, the remainder is 14. Find the remainder when $q(x)$ is divided by $x + 2$.
158
0
2,267.4375
-1
2,267.4375
Let $S=\{1,2, \ldots, 2021\}$, and let $\mathcal{F}$ denote the set of functions $f: S \rightarrow S$. For a function $f \in \mathcal{F}$, let $$T_{f}=\left\{f^{2021}(s): s \in S\right\}$$ where $f^{2021}(s)$ denotes $f(f(\cdots(f(s)) \cdots))$ with 2021 copies of $f$. Compute the remainder when $$\sum_{f \in \mathcal{...
255
The key idea is that $t \in T_{f}$ if and only if $f^{k}(t)=t$ for some $k>0$. To see this, let $s \in S$ and consider $$s, f(s), f(f(s)), \ldots, f^{2021}(s)$$ This sequence has 2022 terms that are all in $S$, so we must have a repeat. Suppose $f^{m}(s)=f^{n}(s)$ with $0 \leq n<m \leq 2021$. Then $f^{2021}(s)=f^{2021+...
0
8,192
-1
8,192
Calculate the limit of the function: $$\lim _{x \rightarrow 0}\left(\frac{\arcsin ^{2} x}{\arcsin ^{2} 4 x}\right)^{2 x+1}$$
1/16
0.5625
7,084.3125
6,222.777778
8,192
Inside the cube $A B C D A_{1} B_{1} C_{1} D_{1}$ is the center $O$ of a sphere with a radius of 10. The sphere intersects the face $A A_{1} D_{1} D$ by a circle with a radius of 1, the face $A_{1} B_{1} C_{1} D_{1}$ by a circle with a radius of 1, and the face $C D D_{1} C_{1}$ by a circle with a radius of 3. Find the...
17
0
7,988.9375
-1
7,988.9375
What is the three-digit number that is one less than twice the number formed by switching its outermost digits?
793
0.875
5,429.8125
5,035.214286
8,192
A right triangle has an area of 120 square units, and a leg length of 24 units. What is the perimeter of the triangle, in units?
60
1
1,370.0625
1,370.0625
-1
Fido's leash is tied to a stake at the center of his yard, which is in the shape of a regular hexagon. His leash is exactly long enough to reach the midpoint of each side of his yard. If the fraction of the area of Fido's yard that he is able to reach while on his leash is expressed in simplest radical form as $\frac{\...
18
0.9375
2,512.5
2,373.066667
4,604
Let $a,$ $b,$ $c,$ $d,$ $e,$ $f,$ $g,$ and $h$ be real numbers such that $abcd = 4$ and $efgh = 9.$ Find the minimum value of \[(ae)^2 + (bf)^2 + (cg)^2 + (dh)^2.\]
24
0.75
5,229.3125
4,241.75
8,192
If $x = -3$, what is the value of $(x-3)^{2}$?
36
Evaluating, $(x-3)^{2}=(-3-3)^{2}=(-6)^{2}=36$.
1
235.125
235.125
-1
Given Lara ate $\frac{1}{4}$ of a pie and Ryan ate $\frac{3}{10}$ of the same pie, then Cassie ate $\frac{2}{3}$ of the pie that was left. Calculate the fraction of the original pie that was not eaten.
\frac{3}{20}
0.9375
3,918.375
3,645.6
8,010
In how many ways can five girls and five boys be seated around a circular table such that no two people of the same gender sit next to each other?
28800
0
6,314.625
-1
6,314.625
Mark rolls 5 fair 8-sided dice. What is the probability that at least three of the dice show the same number?
\frac{1052}{8192}
0
7,270.25
-1
7,270.25
Find some four different natural numbers with the following property: if you add to the product of any two of them the product of the two remaining numbers. you get a prime number.
1, 2, 3, 5
To solve this problem, let's denote the four different natural numbers as \( a \), \( b \), \( c \), and \( d \). The condition given is that for any pair of these numbers, say \( (a, b) \), the expression: \[ ab + cd \] must be a prime number. Similarly, for the other pairs, the following expressions must also be p...
0.0625
6,500
5,176
6,588.266667
In triangle $\triangle ABC$, the sides opposite angles $A$, $B$, and $C$ are denoted by $a$, $b$, and $c$, respectively. It is given that $c \cos B = (2a - b) \cos C$. 1. Find the magnitude of angle $C$. 2. If $AB = 4$, find the maximum value of the area $S$ of $\triangle ABC$.
4\sqrt{3}
0.875
5,728.1875
5,376.214286
8,192
Solve for $r$: $\frac{r+9}{r-3} = \frac{r-2}{r+5}$
-\frac{39}{19}
1
2,667.8125
2,667.8125
-1
Find the largest natural number in which all the digits are different and each pair of adjacent digits differs by 6 or 7.
60718293
0
8,180.6875
-1
8,180.6875
My friend and I both have the same math homework one day. I work at a rate of $p$ problems per hour and it takes me $t$ hours to finish my homework. My friend works at a rate of $2p-4$ problems per hour and it only takes him $t-2$ hours to finish his homework. Given that $p$ and $t$ are positive whole numbers and I do ...
60
1
2,783.125
2,783.125
-1
Real numbers $x_{1}, x_{2}, \cdots, x_{2001}$ satisfy $\sum_{k=1}^{2000}\left|x_{k}-x_{k+1}\right|=2001$. Let $y_{k}=\frac{1}{k} \sum_{i=1}^{k} x_{i}$ for $k=1,2, \cdots, 2001$. Find the maximum possible value of $\sum_{k=1}^{2000}\left|y_{k}-y_{k+1}\right|$.
2000
0
8,192
-1
8,192
Given the plane vectors $\overrightarrow{a}=(1,0)$ and $\overrightarrow{b}=\left( -\frac{1}{2}, \frac{\sqrt{3}}{2} \right)$, find the angle between $\overrightarrow{a}$ and $\overrightarrow{a}+ \overrightarrow{b}$.
\frac{\pi}{3}
0.1875
2,759.9375
3,268.333333
2,642.615385
How many ways are there to put 6 balls into 4 boxes if the balls are indistinguishable, the boxes are distinguishable, and each box must contain at least one ball?
10
0.8125
4,854.125
4,083.846154
8,192
In rectangle $ABCD,$ $AB=15$ and $AC=17.$ What is the area of rectangle $ABCD?$ Additionally, find the length of the diagonal $BD.$
17
1
1,278.5
1,278.5
-1
A track and field team has three sprinters. According to the statistics from their usual training sessions, the probabilities of sprinters A, B, and C finishing a 100m dash within 13 seconds (considered qualified) are $\frac{2}{5}$, $\frac{3}{4}$, and $\frac{1}{3}$, respectively. If the performance of these three sprin...
\frac{9}{10}
0.625
5,498.875
3,883
8,192
A line through the points $(2, -9)$ and $(j, 17)$ is parallel to the line $2x + 3y = 21$. What is the value of $j$?
-37
1
1,516.8125
1,516.8125
-1
Let $S = \{1, 22, 333, \dots , 999999999\}$ . For how many pairs of integers $(a, b)$ where $a, b \in S$ and $a < b$ is it the case that $a$ divides $b$ ?
14
0.0625
8,013.75
5,558
8,177.466667
I have 7 books, three of which are identical copies of the same novel, and the others are distinct. If a particular book among these must always be placed at the start of the shelf, in how many ways can I arrange the rest of the books?
120
0.125
5,210.4375
2,450.5
5,604.714286
Calculate 8 divided by $\frac{1}{8}.$
64
1
1,041.1875
1,041.1875
-1
Find the perimeter of an equilateral triangle inscribed in a circle, given that a chord of this circle, equal to 2, is at a distance of 3 from its center.
3 \sqrt{30}
0.75
5,582.6875
4,712.916667
8,192
In a certain exam with 50 questions, each correct answer earns 3 points, each incorrect answer deducts 1 point, and unanswered questions neither add nor deduct points. Xiaolong scored 120 points. How many questions did Xiaolong answer correctly at most?
42
0.9375
3,248.375
3,406.4
878
Express $213_{8}-142_{7}$ as a base 10 integer.
60
0.9375
2,484.9375
2,104.466667
8,192
Given that square $ABCE$ has side lengths $AF = 3FE$ and $CD = 3DE$, calculate the ratio of the area of $\triangle AFD$ to the area of square $ABCE$.
\frac{3}{8}
0.125
5,423.25
5,968.5
5,345.357143
Given $a \gt 0$, $b \gt 0$, if ${a}^{2}+{b}^{2}-\sqrt{3}ab=1$, determine the maximum value of $\sqrt{3}{a}^{2}-ab$.
2 + \sqrt{3}
0.25
7,680.8125
6,504
8,073.083333
Express this sum as a common fraction: $.\overline{8} + .\overline{2}$
\frac{10}{9}
1
2,013.375
2,013.375
-1
What is the value of $x$ in the equation $16^{16}+16^{16}+16^{16}+16^{16}=2^x$?
66
1
1,515.0625
1,515.0625
-1
Given a class with 21 students, such that at least two of any three students are friends, determine the largest possible value of k.
10
0.0625
7,162.1875
4,619
7,331.733333
Let $\overline{AB}$ be a diameter in a circle of radius $5\sqrt{2}.$ Let $\overline{CD}$ be a chord in the circle that intersects $\overline{AB}$ at a point $E$ such that $BE=2\sqrt{5}$ and $\angle AEC = 45^{\circ}.$ What is $CE^2+DE^2?$
100
1. **Identify the Geometry and Given Information:** - Let $O$ be the center of the circle. - $\overline{AB}$ is a diameter, so $A$, $O$, and $B$ are collinear, and $OA = OB = 5\sqrt{2}$. - $\overline{CD}$ intersects $\overline{AB}$ at $E$ such that $BE = 2\sqrt{5}$ and $\angle AEC = 45^\circ$. 2. **Reflect Po...
0.375
7,679.75
6,987.5
8,095.1
Higher Secondary P4 If the fraction $\dfrac{a}{b}$ is greater than $\dfrac{31}{17}$ in the least amount while $b<17$ , find $\dfrac{a}{b}$ .
\frac{11}{6}
0.1875
7,888
6,826.666667
8,132.923077
Vivek is painting three doors numbered 1, 2, and 3. Each door is to be painted either black or gold. How many different ways can the three doors be painted?
8
Since there are 3 doors and 2 colour choices for each door, there are $2^{3}=8$ ways of painting the three doors. Using 'B' to represent black and 'G' to represent gold, these ways are BBB, BBG, BGB, BGG, GBB, GBG, GGB, and GGG.
1
358.5
358.5
-1
Given two fixed points $A(-2,0)$ and $B(2,0)$, a moving point $P(x,y)$ is located on the line $l:y=x+3$. An ellipse $c$ has foci at points $A$ and $B$ and passes through point $P$. Determine the maximum eccentricity of the ellipse $c$.
\frac{2\sqrt{26}}{13}
0
6,979
-1
6,979
Given the function $f\left(x\right)=\left(x+1\right)e^{x}$. $(1)$ Find the intervals where the function $f\left(x\right)$ is monotonic. $(2)$ Find the maximum and minimum values of $f\left(x\right)$ on the interval $\left[-4,0\right]$.
-\frac{1}{e^2}
0.25
2,910
2,847.25
2,930.916667