Question

Lou has the first 4 encyclopedias lined up on a shelf, A, B, C, and D. If he picks two at random, what is the probability that he picks A first and B second?

A) 1/24 B) 1/6 C) ½ D) 1/12

Answer 1

D

Explanation:

Given:

Lou has the first 4 encyclopedias lined up on a shelf, A, B, C, and D.

To find: probability that he picks A first and B second if he picks two at random

Solution:

Total number of outcomes =
`4!=4(3)(2)(1)=24`

Favourable outcomes are ABCD, ABDC

Number of favourable outcomes = 2

probability that he picks A first and B second = Number of favourable outcomes / Total number of outcomes =
`(2)/(24)=(1)/(12)`