The number of successes and the sample size for a simple random sample from a population are given below.
[ x=8, n=40, H_{0}: p=0.3, H_{a}: p<0.3, ∝=0.10]

a. Determine the sample proportion.
b. Decide whether using the one-proportion z-test is appropriate.
c. If appropriate, use the one-proportion z-test to perform the specified hypothesis test.