A recent survey found that 72 of all adults over 50 own cell phones. You randomly select 36 adults over 50, and ask if he or she owns a cell phone. Decide whether you can use the normal distribution to approximate the binomial distribution.
If so, find the mean and standard deviation, If not, explain why. Round to the nearest hundredth when necessary.
Q. 2Determine whether the following statement regarding a hypothesis test for two population proportions is true or false:
However small the difference between two population proportions, for sufficiently large sample sizes, the null hypothesis of
equal population proportions is likely to be rejected.
A) True B) False
Q. 3Suppose that scores on a test are normally distributed with a mean of 80 and a standard deviation of 8. Read the two questions below.
A. What is the 90th percentile?
B.
What percentage of students score less than 90?
Explain the difference between the two questions. Describe how the method for solving A would differ from the the method for solving B. Be sure to include in your explanation a description of how the table of areas would be used in each case.
Q. 4A researcher wants to study the effects of advertising by female models upon high school boys in small Midwestern towns. The research methodology calls for selecting several small Midwestern towns that have high schools.
What is the frame for this study?
A) high school boys from the small Midwestern towns selected
B) all high school boys from small Midwestern towns
C) all students attending high school from small Midwestern towns
D) high school students from the small Midwestern towns selected
Q. 5Solar energy is considered by many to be the energy of the future. A recent survey was taken to compare the cost of solar energy to the cost of gas or electric energy.
Results of the survey revealed that the distribution of the amount of the monthly utility bill of a 3-bedroom house using gas or electric energy had a mean of 106 and a standard deviation of 10. If the distribution can be considered bell shaped, what percentage of homes will have a monthly utility bill of more than 96?
A) approximately 84 B) approximately 95
C) approximately 32 D) approximately 16
Q. 6Most problems involving normally distributed variables are one of two types.
Type A: Find a probability or percentage, e.g. find the probability that X lies in a specified range.
Type B: Find the observation corresponding to a given probability or percentage.
Suppose that scores on a test are normally distributed with a mean of 80 and a standard deviation of 8. Which of the following questions below are of type B?
a. Find the 80th percentile.
b. Find the cutoff for the A grade if the top 10 get an A.
c. Find the percentage scoring more than 90.
d. Find the score that separates the bottom 30 from the top 70.
e. Find the probability that a randomly selected student will score more than 80.
A) c, e B) b, d C) a, b, c, d D) a, b, d
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