We have 4 boxes and each box is numbered 1, 2, 3 and 4. Each box has either a green or red ball in such a way that at least 1 box contains a red ball and the boxes containing red balls are numbered consecutively. Find the total number of ways in which it can be done.

There are 4 cases only, either all 4 boxes have a red ball, or 3 have a red ball or 2 have a red ball or 1 has a red ball. So, as they are numbered consecutively, total number of ways when only 1 box has red ball = 4 as it can be in any of the four boxes. Similarly, for 2 boxes having red balls, total number of ways = 3, For 3 boxes having red balls, the total number of ways = 2 and for 4 boxes having red boxes, the total number of ways = 1.

Therefore, total number of ways = 4 + 3 + 2 + 1 = 10.

It is the correct answer.