Answer: 10% – Beginning with the 70% who study Maths, it is only possible for a maximum of 25% of all students to not also study English, leaving a minimum of 45% doing both Maths and English. Repeating this procedure for French and German, we subtract a further 15% then 20%, this leaves 10% who must study all 4.

“You descend further into the maze…”

You begin with two equal cups of tea and coffee. You take a teaspoon of tea and put it in the coffee, then take a teaspoon of the mixture and put it back into the tea. Which original cup contains more of the wrong drink?

More tea in the coffee

More coffee in the tea

Equal amounts of the wrong drink in each