Standard normal table
Suppose that 80% of all tax returns lead to a refund. A random sample of 100 tax returns is taken.
a. What is the mean of the distribution of the sample proportion of returns leading to refunds?
b. What is the variance of the sample proportion?
c. What is the standard error of the sample proportion?
d. What is the probability that the sample proportion exceeds 0.85?
use standard normal table to solve
