CE93Engineering Data Analysis
Prof. Joan Walker, Spring 2011
Assignment 11
Due 04/25/2011 11:10 AM
1. If X is a normal random variable with mean
and standard deviation
, then the following is true:
± ²
³
´µ´¶·¸¹º»
Let
¼
½
be the mean of X
1
…X
n
, where all X
i
are normally distributed with mean
and standard
deviation
Show, using the formula above and what you know about expected value / variances,
that the following is true:
¾ ± ²
³¿ÀÁ
´µ´¶·¸¹º»
2. Students in the CE 262 class were asked to report their travel time from their residence to the UC
Berkeley campus. The results are given below:
FEMALES
MALES
time (min)
time (min)
15
45
40
45
40
35
38
20
15
15
25
7
30
20
15
40
30
30
40
45
55
37
30
20
35
7
35
15
15
25
20
20
25
7
19
Assume that these observations represent random samples drawn from the populations of Berkeley
male and female graduate students, which are normally distributed and assumed to have equal
variances. Test the null hypothesis that Berkeley male and female graduate students have the same
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 Spring '08
 Staff
 Variance, female graduate students

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