Question

A box contains blue chips and red chips. A person selects two chips without replacement. If the probability of selecting a blue chip and a red chip is , and the probability of selecting a blue chip on the first draw is , find the probability of selecting the red chip on the second draw, given that the first chip selected was a blue chip.

Answer 1

4/5

Explanation:

Answer 2

Prob ( 2nd Red 'given' 1st Blue ) = 0.8 = 4/5

Explanation:

Prob ( A I B ) = Prob (A ⋂ B) / P (B)

Prob ( 2nd Red 'given' 1st Blue ) = P ( 2nd Red & 1st Blue ) / P ( 1st blue)

P ( 1st blue & 2nd red ) = 32/128 , P ( 1st blue ) = 5/16

So, P ( 2nd Red I 1st Blue ) = ( 32 / 128 ) / ( 5/16 )

= 0.8 = 4/5