MA
214 Probability and Statistics for
Business
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Review Problems for Final Exam
1. Suppose
1/3 of Alaskans support oil drilling on the North Slope. What is the probability that, out of a group
of 12 Alaskans, 10 support oil drilling on the North Slope?
2. If
75% of all hot dog eaters use mustard, 80% use ketchup, and 65% use both, what
is the probability that a mustard user uses ketchup?
3. An
investor has invested in 50 companies, classified by country and industry in
the table below. Calculate the
probability that a Japanese company selected from this group will be a
machinery company.
|
|
Chemical |
Electronic |
Machinery |
|
Germany |
19 |
13 |
2 |
|
Japan |
8 |
6 |
2 |
4. Suppose that a company is giving away
identical free gifts to 4 contest entrants.
There are 20 entrants, 6 of whom are Hispanic. What is the probability that exactly two of the winners will be
Hispanic?
5. Suppose
that PPG's float glass has an average of 0.3 bubbles per square meter. What is the probability that a certain
square meter of glass has 2 or more bubbles?
6. Suppose
the amount of time it takes for a customer to eat a meal at Taco Bell is
normally distributed with mean 20 minutes and standard deviation 6
minutes. Find the probability that a
certain customer takes less than 16 minutes to eat at Taco Bell.
7. Suppose
anthracite coal has an average sulphur content of 100 pounds per ton with a
standard deviation of 4 pounds and bituminous coal has an average sulphur
content of 300 pounds per ton with a standard deviation of 10 pounds. Suppose 50 samples of anthracite coal and 60
samples of bituminous coal are selected.
What is the probability that the average sulphur content of the
bituminous coal will exceed the average sulphur content of the anthracite coal
by more than 202 pounds per ton?
8. A
random sample of 20 homeowners in Indiana have a mean mortgage payment of $800
per month with a standard deviation of $60.
Find a 95% confidence interval for the mean mortgage payment for all
homeowners in Indiana.
9. A
company's retail sales records show that the average monthly expenditure per
person last year was $10. We wish to
see if there is a significant change for this year. Test this with
a = 0.05.
A random sample of 120 customers had an average expenditure of $9.40
with a standard deviation of $0.45.