Bunuel
From a group of 6 boys and 6 girls a volleyball team of 6 players is to be selected. What is the probability that the team consists of 4 boys and 2 girls?
A. \(\frac{5}{33}\)
B. \(\frac{225}{308}\)
C. \(\frac{5}{22}\)
D. \(\frac{225}{311}\)
E. \(\frac{75}{308}\)
Are You Up For the Challenge: 700 Level QuestionsThe number of ways to select 2 girls from 6 girls is 6C2 = (6 x 5)/2! = 15. Similarly, the number of ways to select 4 boys from 6 boys is 6C4 = (6 x 5 x 4 x 3)/(4 x 3 x 2) = 15. Therefore, the total number of ways of selecting 2 girls and 4 boys is 15 x 15 = 225.
The number of ways to select 6 players from 12 players is:
12C6 = (12 x 11 x 10 x 9 x 8 x 7)/(6 x 5 x 4 x 3 x 2) = 2 x 11 x 2 x 3 x 7 = 924
So, the overall probability is 225/924 = 75/308.
Alternate Solution:
Let’s first calculate the probability of the choice B - B - B - B - G - G, in that order:
6/12 x 5/11 x 4/10 x 3/9 x 6/8 x 5/7 = (6 x 5 x 4 x 3 x 6 x 5)/(12 x 11 x 10 x 9 x 8 x 7) = 5/(11 x 4 x 7) = 5/308
Notice that B - B - B - B - G - G can be arranged in 6!/(4!*2!) = (6 x 5)/2 = 15 ways. Thus, the probability that the team consists of 4 boys and 2 girls is (5/308) x 15 = 75/308.
Answer: E