Permutation And Combination:
In a boat, that to be filled by 8 people, there are 4 seats on left and 4 on right. Out of these 8 people 3 insist to sit on left and 2 insist to sit on right. So in how many ways they all can sit.

The number of ways in which we can find seats for the people insisting on sitting on one side of the boat is 4P3*4P2 = 288

The other three people can be arranged in 3! = 6 ways.

Hence, the total number of ways in which they can sit is 288*6 = 1728

You can find the formula sheet for Permutations and Combinations for CAT here.