A bag contains 5 blacks balls and 3 red balls. Two balls ...
A bag contains 5 blacks balls and 3 red balls. Two balls are picked at random without replacement. What is the probability that a black and red balls are picked?
15/28
13/28
5/14
3/14
Correct answer is A
Black balls = 5
Red balls = 3/8
P(B) = 5/8, P(R) = 3/8
P( a Black and a Red) = BR + RB
= (5/8) * (3/7) * (3/8) * (5/7)
= (15/56) + (15/56)
= 30/56
= 15/28
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