A public relations officer of William Paterson University wants to estimate the mean IQ of the university students. If she wants to be 99% confident that her sample mean is off by no more than 3 points, how many students she has to test in order to come up with a valid estimation? A recent study shows that IQ of New Jersey students has standard deviation of 15 points.

She has to test 166 students in order to come up with a valid estimation.

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.

If she wants to be 99% confident that her sample mean is off by no more than 3 points, how many students she has to test in order to come up with a valid estimation?

She test have at least n students, in which n is found . So

Rouding up

She has to test 166 students in order to come up with a valid estimation.

D. If a is a number between 0 and 1, the quotient will be greater than 686.54.

Step-by-step explanation:

If 686.54 is divided by 1, then it equals 686.54. This is because you divide the number 686.54 into 1 part. If you divide 686.54 by more than one part, then it will be less than 686.54 because there is more than 1 part being created. On the other hand, if you divide it by a number <1, then it will have the opposite effect. Example: 686/0.5=1372