Class 11

Math

JEE Main Questions

Permutations and Combinations

$A$ is a set containing $n$ elements. A subset $P_{1}$ is chosen and $A$ is reconstructed by replacing the elements of $P_{1}$. The same process is repeated for subsets $P_{1},P_{2},….,P_{m}$ with $m>1$. The number of ways of choosing $P_{1},P_{2},….,P_{m}$ so that $P_{1}∪P_{2}∪….∪P_{m}=A$ is (a)$(2_{m}−1)_{mn}$ (b)$(2_{n}−1)_{m}$ (c)$(m+n)C_{m}$ (d) none of these