Question

The historical returns on a portfolio had an average return of 21 percent and a standard deviation of 29 percent. Assume that returns on this portfolio follow a bell-shaped distribution.

a.	Approximately what percentage of returns were greater than 79 percent? (Round your answer to the nearest whole percent.)

b.	Approximately what percentage of returns were below –66 percent? (Round your answer to 1 decimal place.)

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The following relative frequency distribution was constructed from a population of 400. Calculate the population mean, the population variance, and the population standard deviation. (Negative values should be indicated by a minus sign. Round your intermediate calculations to 4 decimal places and final answers to 2 decimal places.)

Class	Relative Frequency
−20 up to −10	0.14
−10 up to 0	0.22
0 up to 10	0.32
10 up to 20	0.32

Population mean
Population variance
Population standard deviation

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Thirty-nine cities provided information on vacancy rates (in percent) in local apartments in the following frequency distribution.

Vacancy Rate (in percent)	Frequency
0 up to 3	7
3 up to 6	4
6 up to 9	9
9 up to 12	6
12 up to 15	13

a.	Calculate the average vacancy rate. (Round your answer to 2 decimal places.)

b.	Calculate the variance and the standard deviation for this sample. (Round your intermediate calculations to 4 decimal places and final answers to 2 decimal places.)

Variance
Standard deviation

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The National Sporting Goods Association (NSGA) conducted a survey of the ages of people that purchased athletic footwear in 2009. The ages are summarized in the following relative frequency distribution. Assume the survey was based on 100 individuals.

Age of Purchaser	Percent
Under 14 years old	14
14 to 17 years old	9
18 to 24 years old	12
25 to 34 years old	14
35 to 44 years old	15
45 to 64 years old	22
65 years old and over	14

a.	Calculate the average age of this distribution. Use 10 as the midpoint of the first class and 75 as the midpoint of the last class. (Round your intermediate calculations to 4 decimal places and final answer to 2 decimal places.)

b.	Calculate the sample standard deviation. (Round your intermediate calculations to 4 decimal places and final answer to 2 decimal places.)

Answer 1