Two numbers are selected from the set {1,2,3,4,5} with replacement. The probability that their product is divisible by 3 can be written as a2b2. Then find the least positive integral value of a is
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Solution
No. of favourable ways =9{(1,3),(2,3),(3,3),(4,3),(5,3),(3,1),(3,2),(3,4),(3,5)}
No. of total ways =5×5=52 b=5 9=a2 ⇒a=3