There are 10 balls of different colours. In how many ways is it possible to select 7 of them so asto exclude the white and the black ball ?

There are 24 balls of 6 different sizes in a bag, there being 4 balls of each size in four different colours.In how many ways 4 balls can be selected so that they are of different colours is

A box contain 5 different red and 6 different white balls. In how many ways can 5 balls be selected so that there are at least two balls of each colour ?

A box contain 5 different red and 6 different white balls. In how many ways can 5 balls be selected so that there are at least two balls of each colour ?

A box contains 5 different red and 6 different white balls.In how many ways can 6 balls be selected so that there are atleast 2 balls of each colour?

A box contains 5 different red and 6 different . white balls. In how many ways 6 balls be selected so that are atleast 2 balls of each colour.

A box contains two white balls, three black balls and four red balls. In how many ways can three balls be drawn from the box if at least one black ball is to be included in a draw ?