Question
In a purse, there are 3 two-rupee coins and 4 five-rupee
coins. If you randomly select 4 coins from the purse, what is the probability that you will choose 3 five-rupee coins and 1 two-rupee coin?Solution
ATQ, Number of ways of selecting 3 coins from purse = 7C4 = {[7!/(4!×(7-4!))]} = {7!/(3!×4!)} = {(7×6×5)/(1×2×3)} = 35 Number of ways of selecting 3 five-rupees coins and 1 two-rupees coins = 4C3 × 3C1 = [(4!/(3!×1!)) × (3!/2!×1!)] = 4 × 3 = 12 Required probability =(12/35)
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