There is a bag with only red marbles and blue marbles. The probability of randomly choosing a red marble is 3/10. There are 12 red marbles in the bag and each is equally likely to be chosen. Work out how many marbles in total there must be.
There is a possibility of \(\frac{3}{10}\)to get a red marble and there are 12 red marbles. This is the same as saying \(\frac{3}{10}\)of all the marbles is twelve. Therefore, the total number of marbles are 12 divided by 3 time by 10 which is 40 marbles.
