Question

One ball is selected at random from a bag containing 12 balls of which x are white

a) what is the probability of selecting a white ball?
when a further 6 were white balls were added the probability of selecting a white ball is doubled
b) Find x

Answer 1

a) 12/18

b) 6

Explanation:

If adding 6 white balls doubles the probability then the original amount of balls is 6 and with the new amount of 18, the likelihood of picking a white ball becomes 12/18.