Sample size

I have a population of 101 student services workers who will be taking a customer service skill survey to see if there is a correlation between their customer service skills and the retention numbers at community colleges in the upstate of South Carolina. I need to know what the sample size should be for a population of 101 in full detail. I do have perrmission to ask for help with this issue through University of Phoenix Doctrate Program. Thank you.

For a significant Pearson product-moment correlation at a 0.05 level of significance, a power of 0.80, and a medium effect size, we need 85 people.