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A phone plan charges a fixed monthly amount for a set number of included minutes, plus a per-minute rate for extra minutes. What was the bill for a month with 50 extra minutes?
(1) The fixed monthly amount is $30.
(2) The per-minute rate for extra minutes is $0.20.
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Correct answer
C
The bill equals the fixed monthly amount plus the per-minute rate times the 50 extra minutes.
Statement (1): fixed = $30, but the per-minute rate is unknown, so the extra-minute charge cannot be determined. not sufficient.
Statement (2): rate = $0.20 per minute, but the fixed amount is unknown. not sufficient.
Together: $30 + 0.20 × 50 = $30 + $10 = $40. Unique. neither alone.
The (A)/(B) lure supplies one term of the fixed-plus-variable bill and stops; both the base and the variable rate are needed.
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