The number of combination of 16 things, 8 of which are alike and the rest different, taken 8 at a time is

The number of combination of 16 things 8 of which are a like and the rest different,taken 8 at a time is

Number of ways in which n things of which r alike delta the rest different can be arranged in a circle distinguishing between clockwise and anticlockwise arrangement,is

There are 4n things of which n are alike and the rest different. Find the number of permutations of 4n things taken 2n at a time, each permutation containing the n like things.

The number of combinations of n different of n different things taken r at a time in which p particular things never occur is -

The number of circular permutations of 8 things taken 4 at a time is

The number of circular permutations of 8 things taken 4 at a time is

The number of circular permutation of 8 things taken 4 at a time is

Assertion (A) : The number of selections of 20 distinct things taken 8 at a time is same as that taken 12 at a time Reason (R): C(n, r) = C(n, s), if n = r + s

2.The number of permutations of 8 things taken at a time is 1680, Then r=