AlgebraVery hardSmallest weight at which one courier is cheaper
Algebra practice question
Courier A charges $5 plus $2 per kilogram. Courier B charges $9 plus $1.20 per kilogram. For parcels weighing a whole number of kilograms, what is the smallest weight, in kilograms, for which Courier B is cheaper?
Answer: 6
9 + 1.2w < 5 + 2w gives 4 < 0.8w, so w > 5: the smallest whole number is 6.
Common wrong answers
- If you answered 4
- 4 divides 4 by 1, ignoring the rate difference.
- If you answered 5
- At 5 kg both couriers charge $15.
- If you answered 7
- 7 is not the smallest; 6 already works.
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