STAT 409
Fall 2005
Homework #4
(due Friday, September 25, by 4:00 p.m.)
From the textbook:
6.48
6.410
6.412
6.418
6.82
6.84
6.86
6.52
“Hint”:
Equal variances
6.54
10.
The National Security Agency (NSA) hires you to compute a 95% confidence
interval for the overall average maximum weight (in pounds) its agents can bench
press in a 6repetition set.
Stressing the top secret nature of the data, the NSA
does not make the data available to you, it does not even report the values of the
sample mean and the sample
standard deviation.
The only information you have
is that an 80% confidence interval based on a sample of 14 agents is (273, 300).
Assume the population is approximately normally distributed.
Compute a 95%
confidence interval for the overall average maximum weight NSA agents can
bench press in a 6repetition set.
11.
The following numbers represent the scores on a particular test before and after a
review session for
n
= 5 students:
1
2
3
4
5
Before
26
19
20
15
19
After
30
22
25
19
26
Construct a 95% confidence interval for the average increase is scores.
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 Spring '11
 Stepanov
 Normal Distribution, Variance, Probability theory, overall average maximum

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