GATE2018-1-18

Question

A six-faced fair dice is rolled five times. The probability (in $\%$) of obtaining "ONE" at least four times is

• A. $33.3$
• B. $3.33$
• C. $0.33$
• D. $0.0033$

Answer 1

We can use Binomial Distribution to solve this question.

• P (obtaining ONE at least four times) = P (X=4 or X=5) 

 

• Here, Success = p = obtaining one = 1/6 and failure = q = not obtaining one = 5/6, n = 5,

 

• P (X=4 or X=5) = 5c4 x (1/6)^4 x (5/6)^1 + 5c5 x (1/6)^5 x (5/6)^0

         =    0.0033

• Hence, in percentage (%) = 0.33% ........ ( 0.0033 x 100 )

 

• Therefore, Option C  i.e. 0.33 would be correct answer.