BUSI 230 HW 3.2 Measures of Spread Assignment solutions complete answers
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If all values in a data set are the same, then the sample variance is equal to .
The standard deviation is the square root of the .
For a bell-shaped data set, approximately of the data will be in the interval to .
Find the sample variance and standard deviation for the following sample. Round the answers to two decimal places as needed.
Find the population variance and standard deviation for the following population. Round the answers to two decimal places as needed.
(a) If a population has variance 16, then the population standard deviation is .
(b) If a population has standard deviation 10, then the population variance is .
(a) If a sample has variance 81, then the sample standard deviation is .
(b) If a sample has standard deviation 4, then the sample variance is .
Sports car or convertible? The following table presents the fuel efficiency, in miles per gallon, for a sample of convertibles and a sample of sports cars.
(a) Find the sample standard deviation of the mileage for the sample of convertibles. Round the answer to at least one decimal place.
The sample standard deviation of the mileage for the sample of convertibles is .
(b) Find the sample standard deviation of the mileage for the sample of sports cars. Round the answer to at least one decimal place.
The sample standard deviation of the mileage for the sample of sports car is .
(c) Which sample has greater spread?
The spread of the convertibles is the spread of the sports cars.
House prices: The following table presents prices, in thousands of dollars, of single-family homes for some of the largest metropolitan areas in the United States for March of and March of .
(a) Find the population standard deviation for . Round the answer to at least two decimal places.
In , the population standard deviation, in thousands of dollars, was .
(b) Find the population standard deviation for . Round the answer to at least two decimal places.
In , the population standard deviation, in thousands of dollars, was .
(c) Housing prices increased in most areas from to . Did the spread in house prices increase as well, or did it decrease?
The spread in housing prices from to .
Lunch break: In a recent survey of 655 working Americans ages 25-34, the average weekly amount spent on lunch was $42.73 with standard deviation $2.68. The weekly amounts are approximately bell-shaped.
(a) Estimate the percentage of amounts that are between $34.69 and $50.77.
(b) Estimate the percentage of amounts that are between $37.37 and $48.09.
(c) Between what two values will approximately 68% of the amounts be?
Pay your bills: In a large sample of customer accounts, a utility company determined that the average number of days between when a bill was sent out and when the payment was made is 26 with a standard deviation of 7 days. Assume the data to be approximately bell-shaped.
(a) Between what two values will approximately 95% of the numbers of days be?
Approximately 95% of the customer accounts have payment made between and days.
(b) Estimate the percentage of customer accounts for which the number of days is between and .
