Question

The difference of sample means of two populations is 108.7, and the standard deviation of the difference in sample means is 32. Which statement is true if we are testing the null hypothesis at the 68% confidence level?


A) The difference of the two means is significant at the 68% confidence level, so the null hypothesis must be rejected.



B) The difference of the two means is significant at the 68% confidence level, so the null hypothesis must be accepted.



C) The difference of the two means is not significant at the 68% confidence level, so the null hypothesis must be rejected.



D) The difference of the two means is not significant at the 68% confidence level, so the null hypothesis must be accepted.

Answer 1

The corresponding z-score is equal to the mean divided by the SD, which is 108.7 / 32 = 3.40. The confidence level of 68% is equivalent to a z-score of 1, meaning that the sample z-score is far beyond that of the confidence interval. This means that the difference of the means is significant, and we reject the null hypothesis (choice A).

Answer 2

Answer:

A.

Step-by-step explanation:

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