Question

A teenager is trying to get a driver's license. Assume that his probability of passing the exam on any given attempt is 0.11.

What is the probability that the teenager requires fewer than 6 attempts to get his driver's license?

Answer 1

Answer)

Probability that he passes that exam = 0.11

Probability that he fails = 0.89

There are 5 cases here

First case

He gets license in the very first attempt = 0.11

Second

In second attempt = 0.89*0.11

Third

In third attempt = 0.89*0.89*0.11

Fourth

In fourth attempt = 0.89*0.89*0.89*0.11

Fifth

In fifth attempt = 0.89*0.89*0.89*0.89*0.11

Probability is case 1 + 2 + 3 + 4 + 5 = 0.4415940551