probability question

Question

A company's sales force makes 350 sales calls, with 0.20 probability that sale will be made on a call. What is the probability that fewer than 70 will be made  (round to the nearest 4 decimal places)?

Answer 1

average = .2 x 350 = 70

chance < 70 = 1/2 = 50%

chance exact 70 = 350C280 x [.2]^70[.8]^280 =350!/280! x [.2]^350[4]^280