ECON2300 Homework 6 Homework 6

发布时间：2025-09-29

Hello, dear friend, you can consult us at any time if you have any questions, add WeChat: daixieit

ECON2300

Homework 6

1. (MGH Ch3 Exercise 38) The annual incomes ofthe five vice presidents ofTMV Industries are $125,000; $128,000; $122,000; $133,000; and $140,000. Consider this a population.

a. What is the range?

b. What is the arithmetic mean income?

c. What is the population variance? The standard deviation?

d. The annual incomes of officers of another firm similar to TMV Industries were also studied. The mean was $129,000 and the standard deviation $8,612. Compare the means and dispersions in the two firms.

2. (MGH Ch3 Exercise 44) A consumer watchdog organization is concerned about credit card debt. A survey of 10 young adults with credit card debt of more than $2,000 showed they paid an average of just over $100 per month against their balances. Listed below are the amounts each young adult paid last month. Compute sample variance and standard deviation.

3. The acidity or alkalinity of a solution is measured using pH. A pH less than 7 is acidic, while a pH greater than 7 is alkaline. The following data represent the pH in samples of bottled water and tap water.

(a) Which type of water has more dispersion in pH using the range as the measure of dispersion? (b) Which type of water has more dispersion in pH using the standard deviation as the measure of dispersion?

4. According to the U.S. Census Bureau, the mean of the commute time to work for a resident of Boston, Massachusetts, is 27.3 minutes. Assume that the standard deviation of the commute time is 8.1 minutes to answer the following:

(a) What minimum percentage of commuters in Boston has a commute time within 2 standard deviations ofthe mean?

(b) What minimum percentage of commuters in Boston has a commute time within 1.5 standard deviations ofthe mean? What are the commute times within 1.5 standard deviations of the mean?