PROBABILITY 1

A bag contains 2 red balls and 6 blue balls. Two balls are taken from the bag. What is the probability that they are both red?

Solution

(This is a problem with replacement)

n(R) = 2, n(B) = 6, n(S) = 8

P(R) = n(2)

           n(6)

1st pick = ²/8

2nd pick = ²/8 as well.

P(RR) =  2      x    2

              8            8

P(RR) =   ⁴ /64 = ¹/16       

Therefore Probability of drawing a red ball is 1/16     

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

A bag contains 9 purple stones and 11 blue stones. Two stones are taken from the bag. What is the probability that they are both blue?