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A delivery service charges a base fee plus a fee proportional to the weight of a package. What is the charge for a 10-pound package?
(1) A 4-pound package costs $11 and an 8-pound package costs $17.
(2) The per-pound fee is $1.50.
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Correct answer
A
The charge is base + rate × weight, two unknowns.
Statement (1): two points, (4, 11) and (8, 17). Subtracting, 4 × rate = 6, so rate = 1.5 and base = 11 − 4(1.5) = 5. The 10-pound charge = 5 + 1.5 × 10 = $20. Sufficient.
Statement (2): rate $1.50 per pound, but the base fee is unknown, so the total cannot be determined. Not sufficient.
The (C) lure thinks the explicit rate is needed, but two distinct (weight, cost) points already determine both the base and the rate.
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