Question

In the past few years, outsourcing overseas has become more frequently used than ever before by Canadian and U.S. companies. However, outsourcing is not without problems. A recent survey by Purchasing magazine indicates that 20% of the companies that outsource overseas use a consultant. Suppose 15 companies that outsource overseas are randomly selected.

What is the probability that exactly five companies that outsource overseas use a consultant?

Answer 1

this is a binary probability ... use / don't use

(d + u)^15 = d^15 + 15 d^14 u + ... + 15 d u^14 + u^15

you want the 6th term ... 15C5 d^10 u^5 = 3003 * .8^10 *.2^5