2

4.)
Consumer Banker Association released a report showing the lengths of
automobile leases. The results are as follows.
Lease Length in Months
Percent of Leases
13 - 24
12.7%
25 - 36
37.1%
37 - 48
28.5%
49 – 60
21.5%
More than 60
0.2%
a.)
To estimate the expected lease terms, use the midpoint of each class.
For
the last class, use a midpoint of 66.5 months.
b.)
Using the same method, approximate the standard deviation for the
distribution.
5.)
A factory employs several thousand workers, of whom 30% are Hispanic.
If the
15 members of the union executive committee were chosen from the workers at
random, the number of Hispanics on the committee could be modeled by a
binomial distribution with n = 15, and p
= .30.
a.)
What is the probability that exactly 3 members of the committee are
Hispanic?
b.)
What is the probability that 3 or fewer members of the committee are
Hispanic?
c.)
What is the probability that at most 13 members of the committee are
Hispanic?
d.)
What is the mean number of Hispanics on randomly chosen committees of
15 workers in this factory?
What is the standard deviation?
e.)
Suppose that 10% of the factory workers are Hispanic.
What is the
standard deviation in this case?
What is the standard deviation if only 1%
are Hispanic?
f.)
What does part (e) show about the behavior of the standard deviation of a
binomial distribution as the probability of a success gets closer to 0?

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- Spring '08
- VANES,C.
- Normal Distribution, Standard Deviation, Net Present Value, Probability theory