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2008 AMC 12A Problem 1

Problem 1 of 25EasierAlgebra

A bakery owner turns on his doughnut machine at 8 ⁣: ⁣308\!:\!30 am. At 11 ⁣: ⁣1011\!:\!10 am the machine has completed one third of the day’s job. At what time will the doughnut machine complete the job?

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Solution

From 8 ⁣: ⁣308\!:\!30 am to 11 ⁣: ⁣1011\!:\!10 am is 22 hours 4040 minutes, or 160160 minutes, to complete one third of the job. The whole job then takes 3160=4803 \cdot 160 = 480 minutes, or 88 hours. Adding 88 hours to 8 ⁣: ⁣308\!:\!30 am gives 4 ⁣: ⁣304\!:\!30 pm. Thus, D is the correct answer.

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Problem text and solution from the LIVE past-contest archive. See also the AoPS wiki page for community solutions.