Elementary Statistics Chapter 5 Test A - Elementary...

Elementary Statistics Chapter 5 Test - Form A
Name:___________________________ Course Number: __________ Section Number: _____
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
Provide an appropriate response.
1) Replacement times for T.V. sets are normally distributed with a mean of 8.2 years and a standard
deviation of 1.1 years (based on data from "Getting Things Fixed," Consumers Reports). (a) Find
the probability that a randomly selected T.V. will have a replacement time between 6.5 and 9.5
years. (b) Find the probability that a randomly selected T.V. will have a replacement time
between 9.5 and 10.5 years. These two problems can be solved by the same procedure. Draw the
diagram for each and discuss the difference. Then, explain why the same procedure can be used.
2) The typical computer random-number generator yields numbers in a uniform distribution
between 0 and 1 with a mean of 0.500 and a standard deviation of 0.289. Consider the following
problems. (a) Suppose a sample of size 50 is randomly generated. Find the probability that the
mean is below 0.300. (b) Suppose a sample size of 15 is randomly generated. Find the probability
that the mean is below 0.300. These two problems appear to be very similar. Only one can be
solved by the Central Limit theorem. Which one and why? Use the Central Limit theorem to find
that probability.
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the
question.
Using the following uniform density curve, answer the question.
3) What is the probability that the random variable has a value between 0.6 and 1.4?
A) 0.1000 B) 0.3500 C) 0.2250 D) 0.0250
Assume that the weight loss for the first month of a diet program varies between 6 pounds and 12
pounds,
and is spread evenly over the range of possibilities, so that there is a uniform distribution. Find the
probability of the given range of pounds lost.
4) Less than 10 pounds
A) 5
7 B) 2

3 C) 1
3 D) 1
6
If Z is a standard normal variable, find the probability.
5) The probability that Z lies between -1.10 and -0.36
A) -0.2237 B) 0.4951 C) 0.2237 D) 0.2239
1
Elementary Statistics Chapter 5 Test - Form A
Solve the problem.
6) A bank's loan officer rates applicants for credit. The ratings are normally distributed with a mean
of 200 and a standard deviation of 50. Find P60, the score which separates the lower 60% from the
top 40%.