Number System
An urn contains 9 blue, 7 white and 4 black balls. If 2 balls are drawn at random, then what is the probability that only one ball is white ?
This is a simple division series. Each number is divided by 5. Rule = (1st number / 5 = 2nd number) (2nd number / 5 = 3rd number)....Now, (1000 / 5 = 200), (200 / 5 = 40), (40 / 5 = 8)...So answer is a = 8.
EXAMIANS