Question

In an examination, a candidate has to pass in each of the four subjects. In how many ways can he fail?

• A. $15$
• B. $20$
• C. $25$
• D. $10$

Answer 1

The correct option is A

$15$

Explanation for the correct option:

Finding the number of ways the student can fail:

In an examination, a student can either pass or fail.

So, the total number of ways in which one can pass or fail the examination $=2^4=16$

To pass an examination, a candidate has to pass in each of the four subjects. So, the number of ways in which the exam can be passed $=1$

Therefore, the number of ways the student can fail $=16-1=15$

Hence. option A is correct.