Question: You are a stockbroker making "cold" calls to six digit income customers to generate new business. Over time you have observed that out of every fifty customers called you will convince 20 to use you as a broker. What is the probability that out of the next 20 customers:

a. At least four will make a purchase.

b. The probability that eight or less will not make a purchase.

c. More than six will make a purchase.