We have seen how percentages can miscommunicate severities of diseases with low prevalences. This time we will look at another counterintuitive fact, but here, an opposite perception, showing the contrast between absolute and relative quantities – the potato paradox.
Suppose I have 100 kg of potatoes with a 99% water content. It means 99% water and 1% solids. And if I dry them to reduce their moisture content from 99 to 98%, what is the final weight of my potatoes?
Let’s perform the calculations.
Initial weight of potatoes = 100 kg
Initial water content = 99%
Initial weight of water = 99kg
Initial weight of solids = 1 kg.
Now, drying doesn’t reduce the solids.
Final weight of solids = 1 kg.
Final water content = 98%
Final solid content = 100 – 98 = 2%
If 1 kg of solids represents 2% (0.02) of a mix, the weight of the mix is 1 (kg) / 0.02 = 50 (kg). So the final weight of potatoes is 50 kg, half of the original, and the drying just managed to reduce the moisture content from 99 to 98%!
