Q.
A set contains 2n+1 elements. The number of subsets of this set containing more than n elements is equal to
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a
2n-1
b
2n
c
2n+1
d
22n
answer is D.
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Detailed Solution
Let the original set contains 2n+1 elements, then subsets of this set containing more than n elements, i.e., subsets containing n+1 elements, (n+2) elements, ....2n+1 elements.∴Required number of subsets=Cn+1 2n+1+Cn+2 2n+1+...+C2n 2n+1+C2n+1 2n+1=Cn 2n+1+Cn-1 2n+1+...+C1 2n+1+C0 2n+1=C0 2n+1+C1 2n+1+C2 2n+1+...+Cn-1 2n+1+Cn 2n+1=12[(1+1)2n+1] =1222n+1=22n.
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