Determine the minimum sample size required when you want to be 99% confident that the sample mean is within 0.50 units of the population mean. Assume a standard deviation of 2.9 in a normally distributed population.

a. 130
b. 224
c. 223
d. 129

b. 224

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 the margin of error M as such

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

In this problem:

We want to find n, when So

The nearest integer number to 223.9 is 224.

So the correct answer is:

b. 224

4

step-by-step explanation:

80%

step-by-step explanation: