PROBABILITY 1

A bag contains 12 red balls and 18 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) = 12, n(B) = 18, n(S) = 30

P(R) = n(R)

            n(S)

1st pick = 12/30

2nd pick = 12/30 as well.

P(RR) =  12      x    12

               30            30

P(RR) =   4        

                25          

Therefore Probability of drawing a red ball is 4/25     

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

A bag contains 16 purple stones and 14 blue stones. Two stones are taken from the bag. What is the probability that they are both blue?