Using samples of 200 credit card statements, an auditor found the following:

Sample 1 2 3 4

Number with errors 4 2 5 9

a. Determine the fraction defective in each sample.

b. If the true fraction defective for this process is unknown, what is your estimate of it?

c. What is your estimate of the mean and standard deviation of the sampling distribution of fractions defective for samples of this size?