AlgebraVery hardBlending two coffees to a target price
Algebra practice question
A shop blends coffee costing $12 per kilogram with coffee costing $18 per kilogram to make 10 kilograms of a blend worth $15 per kilogram. How many kilograms of the $12 coffee are used?
Answer: 5
12x + 18(10 − x) = 150 gives 180 − 6x = 150, so x = 5.
Common wrong answers
- If you answered 10
- 10 would give a blend worth $12.
- If you answered 7.5
- 7.5 comes from a target of $13.50 per kilogram.
- If you answered 2.5
- 2.5 has the two coffees swapped.
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