Question

A box contains 12 balls of which some are red in colour. If 6 more red balls are put in the box and a ball is drawn at random, the probability of drawing a red ball doubles than what it was before. Find the number of red balls in the bag.

Answer 1

let the number of red balls = x
probability of red balls = x /12
if 6 more red balls are added :
the no of red balls = x + 6
probability of red balls = x + 6 / 18
since, x + 6 / 18 2 ( x / 12)
therefore, x + 6/18 = x / 6
= > 6x + 36 = 18x
=> x = 3
number of red balls in the bag = 3
hope it will help you... ☺☺

Answer 2

i hope this help you