AP Statistics - Textbook Homework Answers
Chapter 11 โ Significance Tests
11.1 โ Significance Tests โ The Basics
Pg. 691 #2: a) The mean hemoglobin level for all children of this age in Jordan.
b) If ๐ = 12, the sampling distribution is Normal with a mean of 12
and a standard deviation of 1.6
โ50 = 0.2263
c) 11.3 lies far down in the low tail, while 11.8 is fairly close to the
middle. If the mean is 12, observing a mean of 11.8 or smaller would
not be too surprising, but a mean of 11.3 or smaller is extremely
unlikely.
d) No. Since the sample size is large (n=50) the CLT says that the
sampling distribution of ๐ฅ๎ชง is approximately Normal.
e) No. We are told this is a sample, but we donโt know if the children
are randomly selected from a larger population.
Pg. 693 #4: a) ๐ = the mean gas mileage for Larryโs car on the highway
๐ป0: ๐ = 26
๐ป๐: ๐ > 26
b) ๐ = the proportion of teens in your school who rarely or never fight
with their friends.
๐ป0: ๐ = 0.72
๐ป๐: ๐ โ 0.72
#6: a) ๐ป0 and ๐ป๐ have been switched. The null hypothesis should be a
statement of โno change.โ
b) The null hypothesis should be a statement about ๐, not ๐ฅ๎ชง.
c) Our hypothesis should be โsome claim about the populationโ
(whether or not it rains tomorrow is not such a statement).
Pg. 698 #8: a) No. The sample size (n=75) is much larger, so the CLT says that
the sampling distribution of ๐ฅ๎ชง is approximately Normal.
b) ๐ง = 2.45; ๐ โ ๐ฃ๐๐๐ข๐ = 2(0.0071)= 0.0142
c) There is fairly strong evidence against ๐ป0. The p-value is very low.
We would reject ๐ป0.
