A problem that challenges students to consider the effect of combining ratios.

The problem assumes that students understand ratios (they understand that if $1/3$ is red it does not mean that the ratio of red to white is $1:3$) and are able to simplify ratios.

A possible start to using this problem in a classroom could involve asking students to suggest possible combinations of paints A and B (or C and D) and their suggestions could be written up for all to see.

It may be useful to provide students with red and white counters so that they can simulate the effect of mixing the paints. However, counters must be used with care; students need to understand that they must have the same overall number of counters for each paint mixture.

Possible follow up questions:

- What is the ratio of red to white paint in these mixes?
- Can any of these ratios be simplified?
- Will any of these combinations produce the same shade of pink?
- Can you list the mixes in order as they become paler?