UPSC NDA Math Model Paper 2

Since, more than one ball can be placed into a box, all the balls have 2 possibilities for being placed in a box.
∴ The total number of ways in which the balls can be placed =2×2×2×2×2=25=32.
But since, no box should be empty, we have subtract the number of cases where all balls were placed into either the first only or the second box only, which is 1 possible way each.
So, the required total number of ways = 32 - 1 - 1 = 30.