Why isn't "B" the answer?
probability for head = 1/2
similarly probability for tails = 1/2
case 1: all 3 times = head
in that case
probability = 1/2*1/2*1/2 = 1/8
case 2 : all tails then again probability will be 1/8
so total probability will be 1/8+1/8 = 1/4
hope it helps
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