AP Stats
Name___________________________
1. In a study of memory recall, 8 students from a large psychology class were selected at random and given 10
min to memorize a list of 20 nonsense words. Each was asked to list as many of the words as he or she could
remember both 1 hour and 24 hours later as shown below. Is there evidence to suggest that the mean
number of words recalled after 1 hour exceeds the mean recall after 24 hours. Use a 5% level of
significance.
Subject
1 hour later
24 hours later
1
14
10
2
12
4
3
18
14
4
7
6
5
11
9
6
9
6
7
16
12
8
15
12
2. Tennis elbow is thought to be aggravated by the impact experienced when hitting the ball. The following
data reported the force (in newtons) on the hand just after impact on a one-handed back hand drive for
advanced and intermediate players. Determine whether the data support the hypothesis that the mean
force after impact is greater for advance tennis players than it is for intermediate players. Use =0.01.
Advanced
Intermediate
44.7
15.58
26.31
19.16
55.75
24.13
28.54
10.56
46.99
32.88
39.46
21.47
14.32
33.09
3. The Oregon Department of Health web site provides information on the cost-to-charge ratio. Is there
evidence that the mean cost-to-charge ratio for Oregon hospitals is lower for outpatient care than for
inpatient care? Use a 90% confidence interval.
Hospital
Inpatient
Outpatient
1
68
54
2
100
75
3
71
53
4
74
56
5
100
74
6
83
71
4. An experiment was designed to compare the vitamin D plasma half-life for two groups of healthy individuals.
Determine whether the data indicate that the mean half-life is higher for those on a normal diet than for
those on a high fiber diet. Use a 98% confidence interval.
Normal
High Fiber
19.1
12
24
13
28.6
13.6
29.7
20.5
30
22.7
34.8
23.7