Download September 9

Chapter 2 Review
9.9.2016
53.
a)
b)
c)
.0516, or about 5.2% of pregnancies are shorter than 240 days. So
240 days is at approximately the 5th percentile
.5471, or about 55% of pregnancies last between 240 and 270
Longer than 279.44 days
54.
a)
b)
c)
.9452, or about 94.5% of IQ scores are less than 150 (on this
scale), so an IQ score of 150 is at approximately the 95th percentile
.2195, or 21.95% of people have IQ scores between 125 and 150
161.25
55.
a)
b)
c)
We would expect trains to arrive on time about 96% of the time
We would expect trains to arrive early .06% of the time
We want the train to be on time, but not early, so it would make
sense to try to have a be larger.
56.
a)
b)
c)
Approximately 6.7% of lids are too small to fit
Because Z=3.5, it is extremely rare for a lid to be too big
It makes sense for a to be larger than b, because if a lid is too big, it
will lead to spills. If it is too small, customers will simply try a
different lid
57.
a)
b)
c)
.382
.034
To compare options, we want to compare what proportion of the
data would have the train arriving early (to the right of .5). For
option a, it is .0016, and for b it is .0001. Therefore, we prefer
option b because fewer trains will arrive early
58.
a)
b)
c)
4 inches
.013 inches
We prefer reducing the standard deviation, because it will decrease
the number of lids that are too small without increasing the
number of lids that are too big
59.
a)
b)
-1.28 and 1.28
61.3 and 67.7 inches
63.
a)
b)
c)
d)
(histogram top right) Roughly symmetric, peak at 16, varies
from 9.4 to 22.8.
68.2%,95.5%, and 100%. These are very close to 68, 95,
and 99.7
(plot upon request) Except for one possible outlier on each
side, the plot is fairly linear, indicating that it is approximately
normal
All three tests indicate relative normality
64.
a)
b)
c)
d)
(histogram upon request) N=29, Mean=5.4479, StDev=.2209,
Q1=5.2950, Median=5.46, Q3=5.615,
75.86%, 96.55%, and 100%. These results are close to the 68-9599.7 rule
(plot upon request) Normal probability plot is fairly linear,
indicating an approximately normal distribution
All three measures indicate that this distribution is approximately
normal
65. The plot is very close to linear. There are potential outliers on
the low end (lower than expected) and high end (higher than
expected).
66. The shape indicates that the data are skewed to the right.
We can see this from the nearly vertical shape on the left
side, and then the much flatter shape on the right side,
which indicates that those values are larger than would be
expected from a normal distribution.
68. Women’s weights are skewed to the right. We can tell this
because of the difference between the mean and median (in
a symmetric distribution they would be the same), as well
as because the median is not halfway between Q1 and Q3
69. D
70. C
71. B
72. C
73. C
74. C
Review
 Do not turn in—as long as you are working on it in class
today, I will give you credit for it
 Do not have to finish all of them
 I will also post answers online
 Page 109
39,40
 Page 135 75,76
 Page 138 Chapter 2 AP Statistics Practice Test
 Page 136 Chapter 2 Review Exercises