3 girls and 4 boys are seated randomly on a bench. Find the probability that the girls set together and the boys sit together.

The number off total arrangements is 7!(permutation). The number of ways for which the girls and boys sit togehter is 3!4!2. The probability is the division of the number of way by the total possibilities, which gives 2/35. To make less calculations remmeber the fact that the factorial (!) is equal to the multiplication of every number from the starting point to 1, so 4! = 432*1.