Question

There is a bag with only red marbles and blue marbles.
The probability of randomly choosing a red marble is
4
9
.
There are 32 red marbles in the bag and each is equally likely to be chosen.
Work out how many marbles in total there must be.

Answer 1

You can use proportion
Red marbles:total marbles
4 9
32 ?
(32*9)/4
288/4
=72 marbles