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Mix the paint (ratios)

Scale a paint recipe and watch the colour stay the same.

Tins of blue and yellow paint are poured into a bucket. Sliders set how many parts of blue and of yellow go into one batch, and how many batches you make. The bucket's colour depends only on the fraction of blue, so making more batches of the same recipe keeps the colour; changing the recipe changes it.

Mix the paint

Interactive

ratio2 : 3

fraction blue2/5

as a decimal0.4

as a percentage40%

tins in total5

Blue parts per batch2Yellow parts per batch3Number of batches1

The math, with your numbers

\frac{\text{blue}}{\text{total}} = \frac{2}{5} = \frac{2}{5} = 0.4 = 40\%

More batches multiply the top and the bottom by the same number, so the fraction (and the colour) stays put.

Try this

→Set 2 blue : 3 yellow, then add batches. Does the colour change?
→Find two different recipes that give exactly 50% blue.
→Which is bluer: 3 : 4 or 4 : 6? Predict first, then check the percentages.

Want to know why it behaves like this?

The lesson “Fractions, Ratios & Percentages” explains it step by step: Why is 'per' the most useful word in science?

Read the lesson