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General

Easy

Question

# A set of (2n + 1) elements is given. The no. of subsets of the set which contain atmost n elements -

- 2
_{n}
- 2n+1
- 2n –1
- 22n

_{n}## The correct answer is: 22n

### No. of subsets

= ^{2n+1}C_{0 }+ ^{2n+1}C_{1 }+ ^{2n+1}C_{2} +...........+ ^{2n+1}C_{n }= N

(let) We have 2N = ^{2n+1}C_{0} + ^{2n+1}C_{1} .................^{2n+1}C_{2n +1}

2N = 2^{2n + 1}

N = 2^{2n}

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