Dear Aspirant,

the probability that at least one is white is, In a trial the probability of selecting a white ball is 5/20

So, in 4 trials the probability that at least one is white is, S electing a white and then choosing from the rest,

⇒ 1- 81/256that no ball is white

is175/256

Hello Palak,

The solution to your question is quite simple. I guess this is a question from the Probability chapter. The answer ot your question is 0.6836 or simply 68.36%.

The solution can be seen as:

1-((3/4)^4)=0.683 where 3/4 is the required probbility in each pick.

Hope this Helps