In a group of people, each person likes tea or coffee or both. 18 people like only tea and 12 like only coffee. The number of people who like both is one-third of the number of people who like tea. How many people like coffee?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 21
The people who like tea are those who like only tea together with those who like both, and the same holds for coffee.
Let \(x\) people like both; then tea drinkers \(=18+x\)
Both \(=\frac{1}{3}\) of tea drinkers: \(x=\displaystyle\frac{18+x}{3}\)
\(3x=18+x\), so \(2x=18\) and \(x=9\)
Coffee drinkers \(=12+9=21\)
