4 out of 5 dentists prefer a new mouthwash

Question

If 5 dentists are chosen at random from the phone book, what is the approximate probability that exactly 3 of them will prefer the new mouthwash?

 

A) 0.014

B) 0.051

C) 0.173

D) 0.205

Answer 1

there is .8 chance of any given dentist approving, 

so .8 ^3 for the 3 that approve and .2 ^2 for the 2 that do not.

approx 2.05  percent