PROBABILITY 1

A bag contains 4 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) = 4, n(B) = 6, n(S) = 10

P(R) = n(R)

            n(S)

P(R) = 4

          10

1st pick = ⁴/10

2nd pick = ⁴/10 as well.

P(RR) =  4      x    4

             10           10

P(RR) =   ¹⁶ /100 = ⁴/25       

Therefore Probability of drawing a red ball is 4/25     

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 purple?