Problem 1

10.28 For a sample of 12 items from a normally distributed population for which the standard deviation is= 17.0, the sample mean is 230.8. At the 0.05 level of significance, test H0: 220 versus H1:>220.

Please round to 3 decimals.

The critical value is

Problem 2

According to the Federal Reserve Board, the mean net worth of U.S. households headed by persons 75 years or older is $640,000. Suppose a simple random sample of 50 households in this age group is obtained from a certain region of the United States and is found to have a mean net worth of $615,000, with a standard deviation of $120,000.

a. The lower bound of the 95% confidence interval for the population mean is.

b. The upper bound of the 95% confidence interval for the population mean is

Problem 3

10.64 The director of admissions at a large university says that 15% of high school juniors to whom she sends university literature eventually apply for admission. In a sample of 300 persons to whom materials were sent, 30 students applied for admission. In a two-tail test at the 0.05 level of significance, answering the following questions to determine whether we should reject the director's claim:

Please round your answer to 2 decimal places

a. The critical values are +/-

Problem 4

10.60 For a simple random sample, n = 200 p = 0.34. At the 0.01 level, test H0:pi= 0.40 versus H1:pi 0.40 by answering the following questions:

Please round your answer to 2 decimal places

a. The critical values are +/-