A bag contains 4 white balls and some red balls. If the probability of drawing a white ball from the bag is , find the number of red balls in the bag.

Question

Philoid · Accepted Answer

let the number of red ball be x.

total number of red balls = 4+x.

probability of drawing a white ball is =

∴

2(4+x) = 4×5

4+x = 2×5 = 10

X = 10-4 = 6

X = 6

Thus the number of red balls are 6.