Stats questions on test statistics and p-value:

Hello! I believe they way I set up the problem in the first question is accurate. But, I've been working on this second question for a good while. Very frustrated. The formulas I put in don't seem to make sense to me. I've read about finding the p-value, but I am confused. I was wanting to be walked step by step so I know how to set up the equation and where the numbers go in the formula. I want to know how to do this not just an answer.

In one scenario, the students took pictures of themselves squinting and another picture with their eyes wide open. The data were collected for the purpose of testing the null hypothesis that squinting didn't make a difference in the expected age guessed versus the alternative that squinting would make you look older.

Combining multiple sections from a prior semester for a total of forty-seven (n=47) students, the ages guessed by the computer averaged 3.64 years older when the students were squinting with a standard deviation of 12.87 years.

What is the standard error of the mean in this situation?Show your computations.

my answer : s/n = 12.87/47 = 12.87/6.8556546 = 1.87

Find the test statistic (z-score) and then the p-value. Show your computations for the z-score and explain how you found the p-value.

What do you conclude?

(You should arrive at a p-value of about 2 or 3 percent indicating that the null hypothesis -- that squinting has no affect -- is a poor explanation of the data.)