1. The personnel manager of Cumberland Pig Iron Company studies the number of
work accidents in a month and prepared the following probability distribution.
Calculate the mean, variance, and standard deviation of the number of accidents in
one month.
Number of accidents Probability
0 0.40
1 0.20
2 0.20
3 0.10
4 0.10
2. Bank of Hawaii reports that 10% of its credit card customers will stop
pay at some point. The Hilo branch sent out 12 new cards today.
to. How many of the new cardholders do you think will stop paying? Which
is the standard deviation?
b. What is the probability that none of the cardholders stops
pay?
c. What is the probability that at least one defaults?
3. A study related to the cash register lines at Safeway
Supermarket, in the South Strand area, revealed that between 4 and 7 p.m.
On weekends there is an average of four customers in the waiting line. Which
is the probability that when visiting Safeway during this time you will find the following:
to. no customer in line?
b. Four customers in the waiting line?
c. Four or fewer customers in line?
d. Four or more customers waiting?
4. The accounting department of Weston Materials, Inc., manufacturer of carports
detachable, indicates that it takes two construction workers an average of
32 hours, with a standard deviation of two hours, to assemble the Red Barn model.
Assume that the assembly times have
to. Determine the z values of 29 and 34 hours. What percentage of garages
Does it require between 32 and 34 hours of assembly?
b. What percentage of garages require between 29 and 34 hours of assembly?
c. What percentage of garages require 28.7 hours or less of assembly?
d. How many hours does it take to assemble 5% of the garages?