Question

According to a 2009 Reader's Digest article, people throw away approximately 10% of what they buy at the grocery store. Assume this is the true proportion and you plan to randomly survey 77 grocery shoppers to investigate their behavior. What is the probability that the sample proportion exceeds 0.08? Note: You should carefully round any z-values you calculate to 4 decimal places to match wamap's approach and calculations. Answer = (Enter your answer as a number accurate to 4 decimal places.)

Answer 1

We have

Population proportion

Sample proportion

sample size n = 77

we have to find the probability that the proportion exceeds 0.08

Using the formula

setting the given values, we get

this gives us

we can write it using the identity

So, we get

Using z distribution table to get the p value, we get

So, the required probability is 0.7224 (rounded to 4 decimal places)