InterviewSolution
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InterviewSolution
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In how many ways can a prime or an odd number be chosen from {1,2,3,4,5,6,7,8,9,10}? |
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Answer» We form two sets P and O as follows. `P={2,3,5,7}` (primes) and O={1,3,5,7,9} (odd numbers). On applying the general form of Sum Rule we get. `n(PcupO)=n(P)+n(O)-n(PcapO)=4+5-3=6`. We note that the numbers 3,5 and 7 are counted among primes and also among odd numbers. So, we discount 3 (common numbers) from the sum `n(P)+n(O)`. |
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