If the number of ways of selecting r balls with replcement out of n balls numbered 1,2,3……,100 such that the largest number selected is 10 is 271, then r= (A) 4 (B) 5 (C) 3 (D) none of these

The number of ways of selecting 10 balls from unlimited number of red, black, white and green balls, is

If the number of ways of selecting 3 numbers out of 1, 2, 3, ……., 2n+1 such that they are in arithmetic progression is 441, then the sum of the divisors of n is equal to

The total number of ways of selecting 10 balls out of an unlimited number of identical white, red and blue balls is equal to

prove that total number of ways of selection of r points out of n points in a row such that no two of them are consecutive C(n-r+1,r)

There are four balls of different colours and four boxes of colours, same as those of the balls. The number of ways in which the balls, one in each box, could be placed such thast a ball does not go to a box of its own colour is: (A) |__4-1 (B) 9 (C) |__3+1 (D) none of these

the total number of ways of selecting two number from the set {1,2,3,4,…..3n} so that their sum divisible by 3 is equal to -

Find the number of ways of selecting 9 balls from 6 red balls,5 white balls and 5 blue balls if each selection consists of 3 balls of each colour.