Agroup of statistics students decided to conduct a survey at their university to find the average (mean) amount of time students spent studying per week. assuming a population standard deviation of three hours, what is the required sample size if the error should be less than a half hour with a 99% level of confidence? select one: a. 196 b. 239 c. 15 d. 16

b. 239

Step-by-step explanation:

We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Ztable as such z has a pvalue of .

So it is z with a pvalue of , so

Now, find M as such

In which is the standard deviation of the population and n is the size of the sample.

In this problem, we have that:

So a sample of at least 239 is required.

The correct answer is:

b. 239

.95

step-by-step explanation: