Question

10 different names are put into a computer, and one of them is Colin, the computer chooses 2 names at random. The computer is set so that the same name can be chosen twice. What is the probability that Colin is chosen at least once?

Answer 1

0.19

Explanation:

Given that :

Total possible outcomes = 10

If the same name can be chosen twice, then probability is with replacement ;

Probability = required outcome / Total possible outcomes

Required outcome = number of Collins in name = 1

Probability of choosing Collins atleast once ;

2[P(Collins) * P(not Collins)] + P(Collins) * P(Collins)

P(colins) = 1/10

P(not Collins) = 9/10

2(1/10 * 9/10) + (1/10 * 1/10)

2(9/100) + (1/100)

18/100 + 1/100

19/100

= 0.19