Question

There are 5 questions in a question paper. In how many ways can a boy solve one or more questions?

Answer 1

The boy can dispose of each question in two ways. He may either solve it or leave it. Thus the number of ways of disposing of all the questions = 2⁵. 

But this includes the case in which he has left all the questions unsolved. 

Hence the total number of ways of solving the paper = 2⁵ – 1 = 31.