Question

The books namely Math, English, Arabic, Physics, and Chemistry are arranged in the rack by the librarian. What is the probability of Math book will be kept in first place?

Answer 1

P(4,4) / P(5/5) = 1/5

Explanation:

Total possibility:

All the 5 books can be arranged in a rack with P(5,5)=5! ways

Favorable Possibility:

Math book is kept in a first place, it mean that it is fixed

So remaining 4 books and that can be arranged in P(4,4)=4! ways

Hence,

Probability= number of favorable cases / total number of possibilities

Probability = P(4,4) / P(5,5) = 4! / 5! = 1/5