There is only 1 way in which a student can answer all the questions correctly

so no. Of ways in wich a student fail to get all the answers is the same as the no of ways in which he attempts atleat 1 ques incorrectly

so this is equal to total no. Of ways - 1(way in which all answers are correct)

= 4^3-1

Akshay Jain

Masters in Economics

Delhi School of Economics

2013-15