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1. a. Houston Chronicle, Des Moines Register, Chicago There are no scores in the high 70's. |
Tribune, Washington Post |
b. Capital One, Campbell Soup, Merrill Lynch, 13: a 2 23 Stem units: 1.0 |
Prudential 3 2344567789 Leaf units: .10 |
c. Bill Jasper, Kay Reinke, Helen Ford, David Menendez. 4 01356889 |
d. 1.78, 2.44, 3.50, 3.04 5 00001 114455666789 |
4. a Inatampe of 100DVD plage, wha wet chances 6 | ooorz2zzza444seooresse9 |
that more than 20 need service while under warranty? B45555 |
What are the chances that none need service while still § 02255488 |
under warranty? 9 012233335666788 |
b. What proportion of all DVD players of this brand and lo | 2344455688 |
model will need service within the warranty period? 11 | 2335999 |
5. a, No, the relevant conceptual population is all scores of B 7 |
all students who participate in the SI in conjunction ; |
with this particular statistics course. 14 | 36 |
b. The advantage of randomly allocating students to the 15 0035 |
two groups is that the two groups should then be fairly 16 |
comparable before the study. If the two groups perform 17 |
differently in the class, we might attribute this to the 1s | 9 |
treatments (SI and control). If it were left to students to |
choose, stronger or more dedicated students might b. A representative value could be the median, 7.0. |
gravitate toward SI, confounding the results. ¢. The data appear to be highly concentrated, except for |
c. If all students were put in the treatment group there a few values on the positive side |
would be no results with which to compare the d. No, there is skewness to the right, or positive |
treatments skewness. |
7. One could generate a simple random sample of all single The vals, 1B sppeane'tn be an outlier; being mate |
: than two stem units from the previous value. |
family homes in the city, or a stratified random sample |
by taking a simple random sample from each of the ten 15, a, ———H—-——_ |
district neighborhoods. From each of the homes in the Relative |
sample the necessary data would be collected. This Naaabar frequency |
would be an enumerative study because there exists a - |
finite, identifiable population of objects from which to nonconforming Frequency (Freq/60) |
sample. 0 7 0.117 |
9. a. There could be several explanations for the variability 1 12 0.200 |
of the measurements. Among them could be measuring 2 13 0.217 |
error, (due to mechanical or technical changes across 3 14 0.233 |
measurements), recording error, differences in 4 6 0.100 |
weather conditions at time of measurements, etc. 3 3 0.050 |
b. This study involves a conceptual population. There is é 3 0.050 |
no sampling frame a ( ai |
1. 61 034 8 1 0.017 |
6h 667899 1.001 |
71 00122244 Doesn't add exactly to | because relative |
Th Stem = tens frequencies have been rounded |
81 001111122344 Leaf = ones |
8h 5557899 |
91 03 |
oh 58 |
814 |
--- Trang 828 --- |
Chapter! 815 |
b. .917, 867, | ~.867 = .133 —— |
¢. The center of the histogram is somewhere around bd. Class Freq Rel freq Density |
2 or 3 and it shows that there is some positive — |
skewness in the data. 0 < 50 8 0.08 0016 |
50-< 10013 0.13 0026 |
AEs Pes 100-< 1501 0.11 0022 |
© 242 150- < 200 21 0.21 0042 |
d. The histogram is very positively skewed. 200-< 300 26 0.26 0026 |
300-< 40012 0.12 0012 |
19. a. The number of subdivisions having no cul-de-sacs is, 400- < 500 4 0.04 “0004 |
17/47 = .362, or 36.2%. The proportion having at 500: |
g - < 600 3 0.03 0003, |
least one cul-de-sac is 30/47 = .638, or 63.8% 600. < 9002 ne “S000 |
i00 1.00 |
yr Count Percent |
ie) EF 36.17 coe |
1 22 46.81 |
2 6 12.77 |
. pe Class Freq Class Freq |
5 1 2.13 10- < 20 8 Lie < 12 2 |
N=47 20- < 30 14 12 < 13 6 |
2362, .638 30- < 40 8 13-<14 7 |
40- < 50 4 14<15 9 |
OS 50- < 60 3 15-< 16 6 |
b. cad Count Percent 60- < 70 2 1.6-< 1.7 4 |
TT 70- < 80 a 17 < 18 5 |
° 13 27.66 40 18-< 1.9 1 |
1 ts 23.40 40 |
2 3 6.38 a |
3 7 14.89 |
4 5 10.64 |
The original distribution is positively skewed |
5 3 6.38 |
The transformation creates a much more symmetric, |
6 3 6.38 |
mound-shaped histogram. |
8 2 4.26 a |
N=47 : |
25. a. Class interval Freq Rel. Freq. |
-894, .830 |
0-< 50 9 0.18 |
2 a —§ A 50-< 100 19 0.38 |
Class Freq Rel freq 100-< 150 ul 0.22 |
i 150-< 200 4 0.08 |
O=5 100 at O71 200-< 250 2 0.04 |
100- < 200 32 0.32 b50-< 400 5 004 |
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