A, B and C can do a work in 20, 30 and 60 days respectively. In how many days can A complete the work, if he is assisted by B and C on every third day?

The work capacity of A is three times more than that of B. Both of them together can complete a work in 15 days. In how many days will A alone complete that work?

If a cube is to be painted with red and blue colour in such a way that each face gets exactly one colour, then in how many ways this cube can be painted?

From a group of 7 men and 6 women, five persons are to be selected to form a committee so that at least 3 men are there on the committee. In how many ways can it be done?

A man has 7 relatives (4 women and 3 men). His wife also has 7 relatives (3 women and 4 men). In how many ways can they invite 3 women and 3 men so that 3 of them are man's relatives and 3 of them ar…

In how many ways a committee, consisting of 5 men and 6 women can be formed from 8 men and 10 women?