Pleas help me answer this Stats math problem

Question

According to a 2009 Reader's Digest article, people throw away about 7% of what they buy at the grocery store. Assume this is the true proportion and you plan to randomly survey 88 grocery shoppers to investigate their behavior. What is the probability that the sample proportion does not exceed 0.13?

Note: Do not round your answers throughout the problem until the very end. I encourage you to use Excel for these problems.

Answer =  (Enter your answer as a number accurate to 4 decimal places.)

Answer 1

phat is sample proportion

p = population proportion

use z = (phat - p)/sqrt(p*(1-p)/n))

here p = 0.07 and phat = 0.13 and n = 88

P(phat < 0.13) = P(z < (0.13 - 0.07)/sqrt(0.07*0.093/88) = P(z < 2.21) = 0.9864