In: Statistics and Probability
A committee of 4 is chosen at random from a group of 7 women 5 men. Find the probability that the committee contains at least one man.
without replacement
Solution:
Given:
7 women
5 men
Total = 12
We have to make committee of 4 and find the probability that the committee contains at least one man.
P( the committee contains at least one man) =.............?
P( the committee contains at least one man) = 1 - P( the committee contains NO man )
P( the committee contains at least one man) = 1 - P( the committee contains all four women )
Thus first find:
P( the committee contains all four women ) = ........?
4 women from 7 women can be selected in 7C4 ways and any 4 persons can be selected from 12 people in 12C4 ways.
Thus
P( the committee contains all four women ) = 7C4 / 12C4
Use following combination formula to find number of combinations:
Thus
P( the committee contains all four women ) = 7C4 / 12C4
P( the committee contains all four women ) = 0.070707
Thus
P( the committee contains at least one man) = 1 - P( the committee contains all four women )
P( the committee contains at least one man) = 1 - 0.070707
P( the committee contains at least one man) = 0.929293
P( the committee contains at least one man) = 0.9293
( Round answer to specified number of decimal places)