Question

11.9.10 Assigned Media 3 Ques A bag contains 6 red balls and 7 green balls. You plan to select 2 balls at random. Determine the probability of selecting 2 green balls. The problem is to be done without replacement. Use combinations to determine the probability The probability is (Type an integer or a simplified fraction.) (1,1) More Enter your answer in the answer box and then click Check Answer All parts showing Clear All Final Che • Previous

Answer 1

Solution:

Given: a bag contains 6 red balls and 7 green balls, thus total balls = 6+7=13 balls

We have to find:

P( 2 green balls) = .........?

Any 2 balls can be selected from 13 balls in 13C2 ways and

2 green balls can be selected  from 7 green balls in 7C2 ways

Thus

P(2 Green Balls) = 72 13C2

we use combination formula:

n! nort! x (n-1)!

7! 7X 6 X 5! 7 x 6 2! x 5!2x1 x 5!2x1 702 + 2! * (7 - 2)!

13! 13C2 = 2 x (13 - 2)! 13! 13 x 12 x 11! 13 x 12 2! x 11!= 2x1x112x1

thus we get:

P(2 Green Balls) = 72 13C2

P(2 Green Balls) = 4

21/3 P(2 Green Balls) = 78/13

P(2 Green Balls) =