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You should do the test with Z rather than t when

false
The numbers are sampled from a normal distribution.
Both the Z and t tests assume normality
false
The sample size is large.
Before the discovery of the t distribution, the Z test was used for large sample sizes. However,
saample size is not the deciding factor.
false
The sample standard deviation is known.
The sample standard deviation is always known.
true
The population standard deviation is known.
Assume you know the standard deviation of test scores is 10 and that the distribution is normal. You sample 16 scores and find that the sample mean is 25. Find the p value for a two-tailed test of the hypothesis that the population mean is 20.

.0455
0.01
The standard error of the mean is 2.5. You then find the probability of a sample mean more than 25-20 = 5 from the population mean of 20. This is the probability outside 15 and 25 given a distribution with a mean of 20 and a standard deviation of 2.5. The probability is .0455.
What is the standard deviation (s) of these sample data?

0
0.01
Make sure you divide by N-1. showCorrectAnswer
What is the estimated standard error of the mean based on these sample data (These are the same data as the previous question.)?

0
0.01
You divide s by the square root of N. showCorrectAnswer
What is the value of t testing the null hypothesis that the population mean is 0 (These are the same data as the previous question.)?

0
1.7219
0.01
You divide M = 1.625 by the standard error of the mean (.9437) to get 1.72.
What is the value of two-tailed probability value testing the null hypothesis that the population mean is 0 (These are the same data as the previous question.)?

0
.1288
0.01
You use N-1 = 7 degrees of freedom. p = .1288