Question

CHALLENGE ACTIVITY 5.7.1: Hypothesis test for the difference between two population means. Start An electrician wants to know whether batteries made by two manufacturers have significantly different voltages. The voltage of 95 batteries from each manufacturer were measured. The population standard deviations of the voltage for each manufacturer are known. The results are summarized in the following table. D-D-D- 3 Manufacturer Sample mean voltage (millivolts) Population standard deviat A 125 5 B 124 3 What type of hypothesis test should be performed? Select What is the test statistic? Ex: 0.129 Does sufficient evidence exist to support the claim that the voltage of the batteries made by the two manufacturers is different at the a = 0.1 significance level? Select Check Next

Answer 1

We have a comparison of the means test. Since population SD is known, we can conduct a z test for the means here.

Test statistic: (125-124)/√(5^2 + 3^2)/95 = 1.672

P-value: 2P(z>1.672) = 0.0945 (from the standard normal distribution tables)

Since the p-value of this test < significance level of 0.10, we have sufficient evidence to Reject H0 and conclude that yes the means are significantly different at the 10% level of significance.