Question

A bag contains 6 red balls and some blue balls. If the probability of drawing a blue ball the bag is twice that of a red ball, find the number of blue balls in the bag.

Answer 1

No of red balls = 6

Let no. of blue balls = x

Total no. of possible outcomes = 6 + x(total no. of balls)

P(E) = (No.of favorable outcomes)/(Total no.of possible outcomes)

P(blue ball) = 2 P(red ball)

⇒x /(x+6) = 2(6)/(x+6)

⇒ x = 2(6)

x = 12

∴ No of blue balls = 12