Probability Question 118

Question: Ten students are seated at random in a row. The probability that two particular students are not seated side by side is

Options:

A) $ \frac{4}{5} $

B) $ \frac{3}{5} $

C) $ \frac{2}{5} $

D) $ \frac{1}{5} $

Show Answer

Answer:

Correct Answer: A

Solution:

Total ways $ =10! $

Two boys can sit side by side in $ 2\times 9! $ ways.

So probaibility $ =\frac{2\times 9!}{10!}=\frac{1}{5} $

Thus the probability that they are not seated together is $ 1-\frac{1}{5}=\frac{4}{5}. $