Question

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A teacher wants to compare scores on a geology exam for two classes. The difference between the sample means is 21.4. If the standard deviation of the distribution of the difference between sample means is 16.66, and she is testing the hypothesis at the 68% confidence level, which statement is true?

Answer 1

@cj49

Answer 2

The difference between the two means is significant, so the null hypothesis must be accepted.
The difference between the two means is not significant, so the alternative hypothesis must be rejected.
The difference between the two means is not significant, so the null hypothesis must be rejected.
The difference between the two means is not significant, so the alternative hypothesis must be accepted.
The difference between the two means is significant, so the alternative hypothesis must be accepted.

Answer 3

z = 21.4 / 16.66 = 1.2845
Sample sizes unknown so we assume z instead of t.
The critical two-tailed z value for 68% confidence interval is 0.99
1.2845 > 0.99 , so reject H0 of equal means
The difference between the two means is significant, so the alternative hypothesis must be accepted.

Answer 4

awesome thank you!

Answer 5

any tym mate...