A survey of all medium- and large-sized corporations showed that 64% of them offer retirement plans to

Question:

A survey of all medium- and large-sized corporations showed that 64% of them offer retirement plans to their employees. Let p̂ be the proportion in a random sample of 50 such corporations that offer retirement plans to their employees. Find the probability that the value of p̂ will be
a. Between .54 and .61
b. Greater than .71