Question

There is a bag with only milk and dark chocolates.

The probability of randomly choosing a dark chocolate is
4
9
.
There are 32 dark chocolates in the bag and each is equally likely to be chosen.
Work out how many milk chocolates there must be.

Answer 1

Call the amount of milk chocolates : x

The probability of randomly choosing a dark chocolate is 4/9 -> The ratio of dark chocolates to the total amount of chocolates is 4:9

-> The ratio of dark chocolates to milk chocolates = 4:(9-4) = 4:5

So, there must be 32 : 4 x 5 = 40 milk chocolates.

Recheck : There are 32 + 40 = 72 chocolates in the bag, the probability of picking a dark chocolate is 32 : 72 = 4/9 (satisfied)