Question

In a question paper, there are four multiple choice type questions. Each question has five choices with only one choice for its correct answer. What is the total number of ways in which a candidate will not get all the four answers correct?  

(a) 19 (b) 120 (c) 624 (d) 1024

Answer 1

(c) Since, every question has five options, so no. of choices for each question = 5 

∴ total no. of choices = 5 × 5 × 5 × 5 = 625 

Now, no. of choices of all correct answer = 1 

Hence, no of choices for all the four answers not correct 

= total no. of choices – no. 

of choices of all correct  answer = 625 – 1 = 624