PROBABILITY 9

A bag contains 10 red balls and 8 blue balls. Two balls are taken from the bag. What is the probability that they are both blue?

Solution

(This is a problem with replacement)

n(R) = 10, n(B) = 8, n(S) = 18

P(B) = n(B)

            n(S)

1st pick = 8/18

2nd pick = 8/18 as well.

P(B) =  8      x    8

          18          18

P(B) =   324    =      16 

             196           81  

  

Therefore Probability of drawing a blue ball is 16/81     

TRY THIS ..............

A bag contains 8 purple stones and 12 blue stones. Two stones are taken from the bag. What is the probability that they are both blue?