Question

A bag contains 11 red balls, 9 blue balls and x yellow balls. The probabilty of choosing a yellow ball at random is 1/6. What is the probability of not getting a blue ball.

Answer 1

i think there 4 yellows

Answer 2

prob(yellow) = x/(20+x)
but we know this is 1/6

x/(20+x) = 1/6
6x = 20+x
x = 4

so there are 24 balls, of which 9 are blue

so Prob(blue) = 9/24 = 3/8