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Math 105001
Review Problems for Midterm Exam 2
1. Given that
X
is a normal random variable with mean
μ
= 47 and standard deviation
σ
= 6
.
2, ﬁnd
(a)
P
(
X
≤
60).
(b)
P
(
X
≥
50).
(c)
P
(50
≤
X
≤
60).
2. The personnel oﬃce at a large electronics ﬁrm regularly schedules job interviews and
maintains records of the interviews. From the past records, they have found that the
length of a ﬁrst interview is normally distributed, with mean
μ
= 35 minutes and standard
deviation
σ
= 7 minutes.
(a) What is the probability that a ﬁrst interview will last 40 minutes or longer?
(b) Nine ﬁrst interviews are usually scheduled per day. What is the probability that the
average length of time for the nine interviews will be 40 minutes or longer?
3. Suppose the mean systolic blood pressure (
μ
) of normal adults is 120 (mm Hg) and the
stand deviation (
σ
) is 5. If a sample of 100 adults is randomly selected, ﬁnd the probability
that the sample mean (
¯
X
) will be between 119.5 and 121.5 (mm Hg).
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This note was uploaded on 11/19/2010 for the course R 102 taught by Professor Morrison during the Spring '10 term at Rutgers.
 Spring '10
 MORRISON

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