Question

A bag contains 240 marbles. Some are red and the rest are black. There are 27 marbles for every 13 black marbles. How many red marbles are in the bag? Explain your reasoning.

Answer 1

162 red marbles, 78 black marbles

Explanation:

The ratio of red marbles to black marbles is 27 to 13. We have:

`27r + 13r = 240`

`40r = 240`

`r = 6`

So we have 27(6) = 162 red marbles and 13(6) = 78 black marbles.