Author Question: Consider the following hypotheses test. Ho: 80 Ha: < 80 A sample of 121 provided a sample mean ... (Read 78 times)

bio_gurl · **on:** Jun 24, 2018

Consider the following hypotheses test. Ho: 80 Ha: < 80 A sample of 121 provided a sample mean of 77.3 . The population standard deviation is known to be 16.5.
a. Compute the value of the test statistic.
b. Determine the p-value; and at 93.7 confidence, test the above hypotheses.
c. Using the critical value approach at 93.7 confidence, test the hypotheses.

Question 2

A sample of 64 account balances from a credit company showed an average daily balance of 1,040 . The standard deviation of the population is known to be 200 . We are interested in determining if the mean of all account balances (i.e., population mean) is significantly different from 1,000.
a. Develop the appropriate hypotheses for this problem.
b. Compute the test statistic.
c. Compute the p-value.
d. Using the p-value approach at 95 confidence, test the above hypotheses.
e. Using the critical value approach at 95 confidence, test the hypotheses.

chevyboi1976 · **Reply #1 on:** Jun 24, 2018

Answer to Question 1

a. Z = -1.8
b. p-value = 0.0359 < 0.063, reject Ho
c. test statistic Z = -1.8 < Z.063 = -1.53, reject Ho

Answer to Question 2

a. Ho: = 1000
Ha: 1000
b. 1.60
c. 0.1096
d. The p-value = 0.1096, which is larger than = 0.05 (95 confidence). Hence, the null hypothesis is not rejected; and we conclude that there is not sufficient evidence to indicate that the advertising campaigns have been effective.
e. In Part b, the Z statistic was computed and its value was 1.60 . Since 1.60 is between -1.96 and 1.96, the null hypothesis cannot be rejected; and we conclude that there is no evidence that the mean is significantly different from 1,000.