Probability Question 388

Question: The probability that in the random arrangement of the letters of the word ‘UNIVERSITY’ the two I’s does not come together is

Options:

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

B) 1/5

C) 1/10

D) 9/10

Show Answer

Answer:

Correct Answer: A

Solution:

Total no. of arrangements of the letters of the word UNIVERSITY is $ \frac{10!}{2!} $ . No. of arrangements when both I’s are together $ =9! $

So. The no. of ways in which 2 I’s do not together $ =\frac{10!}{2!}-9! $

$ \therefore $ Required probability $ =\frac{\frac{10!}{2!}-9!}{\frac{10!}{2!}}=\frac{10!-9!2!}{10!} $

$ =\frac{10\times 9!-9!2!}{10!}=\frac{9![10-2]}{10\times 9!}=\frac{8}{10}=\frac{4}{5} $