Question
A bag holds 'a' red bands and 5 green bands. If two
bands are drawn sequentially at random without replacement, the probability that both selected bands are red is given as 3/7 . Determine the value of 'a'.Solution
ATQ, a*(a-1)/ [(a+5)*(a+4)] = 3/7 By using optional method, (10*9)/ (15*14) = 90/210 = 3/7 a = 10
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