Statistical Analysis I
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1. A recent article in the Myrtle Beach Sun Times reported
that the mean labor cost to repair a color television is $90 with a
standard deviation of $22. Monte’s TV Sales and Service completed
repairs on two sets this morning. The labor cost for the first was
$75 and it was $100 for the second. Compute z values
for each and comment on your findings.
2. The mean of a normal distribution is 400 pounds. The standard
deviation is 10 pounds.
a. What is the area between 415 pounds and the mean?
b. What is the area between the mean and 395 pounds?
c. What is the probability of selecting a value at random and
discovering that it has a value of less than 395 pounds?
3. The monthly sales of mufflers in the Richmond, VA area follow the
normal distribution with a mean of 1200 and a standard deviation of
225. The manufacturer would like to establish inventory levels such
that there is only a 5% chance of running out of stock. Where should
the manufacturer set the inventory levels?
4. Research on new juvenile delinquents revealed that 38% of them
committed another crime.
a. What is the probability that of the last 100 new juvenile
delinquents put on probation, 30 or more will commit another crime?
b. What is the probability that 40 or fewer of the delinquents will
commit another crime?
c. What is the probability that between 30 and 40 of the delinquents
will commit another crime?
5. An Air Force study indicates that the probability of a disaster
such as the January 28, 1986 explosion of the space shuttle
Challenger was 1 in 35. The Challenger flight was the
a. How many disasters would you expect in the first 25 flights?
b. Use the normal approximation to estimate the probability of at
least one disaster in 25 missions.
to the rubric below for the grading criteria for this assignment.