Assume the probability that you will make a sale on any give

Assume the probability that you will make a sale on any given telephone call is 0.19. Find the probability that you a. make your first sale on the fifth call b. make your first sale on the first, second, or third call c. do not make a sale on the first three calls.

Solution

a.

First 4 times no sale and last one is sale.

Probability = (1-0.19)^4 * 0.19 = 0.082 Answer

b.

Probability you make sale on first call =0.19

Probability you make sale on second call =(1-0.19) *0.19

Probability you make sale on third call =(1-0.19)^2 *0.19

Probability you make sale on first,second or third call = 0.19 + (1-0.19) *0.19 + (1-0.19)^2 *0.19

=0.469 Answer

c)

P(do not make sale on first three calls ) = (1-0.19)^3 = 0.531 Answer