Given the following hypothesis:

H0 : μ = 400

H1 : μ ≠ 400

For a random sample of 12 observations, the sample mean was 407 and the sample standard deviation 6. Answer the following questions using the .01 significance level.

(a)
State the decision rule? (Negative amount should be indicated by a minus sign. Round your answers to 3 decimal places.)

Reject H0 and accept H1 when the test statistic is the interval (, ).

(b) The value of the test statistic is . (Round your answer to 3 decimal places.)

(c) What is your decision regarding H0 ?



Scrapper Elevator Company has 20 sales representatives who sell their product throughout the United States and Canada. The number of units sold by each representative is listed below. Assume these sales figures to be the population values.

2 3 2 3 3 4 2 4 3 2 2 7 3 4 5 3 3 3 3 5

Picture Click here for the Excel Data File

(b) Compute the mean of the population. (Round your answer to 1 decimal place.)

Mean of the population

CRA CDs Inc. wants the mean lengths of the "cuts" on a CD to be 135 seconds (2 minutes and 15 seconds). This will allow the disk jockeys to have plenty of time for commercials within each 10-minute segment. Assume the distribution of the length of the cuts follows the normal distribution with a population standard deviation of 8 seconds. Suppose we select a sample of 16 cuts from various CDs sold by CRA CDs Inc.

(a) What can we say about the shape of the distribution of the sample mean?

Sample mean

(b) What is the standard error of the mean?

Standard error of the mean seconds.

(c)
What percent of the sample means will be greater than 140 seconds? (Round your answer to 2 decimal places. Omit the "%" sign in your response.)

Percent %

(e)
What percent of the sample means will be greater than 128 but less than 140 seconds? (Round your answer to 2 decimal places. Omit the "%" sign in your response.)

Percent %