2013 AIME II Problem 1

Attempt Problem 1 of the 2013 AIME II below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2013 AIME II solutions, or check the answer key.

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1.

Suppose that the measurement of time during the day is converted to the metric system so that each day has 1010 metric hours, and each metric hour has 100100 metric minutes. Digital clocks would then be produced that would read 9:999{:}99 just before midnight, 0:000{:}00 at midnight, 1:251{:}25 at the former 3:003{:}00 AM, and 7:507{:}50 at the former 6:006{:}00 PM. After the conversion, a person who wanted to wake up at the equivalent of the former 6:366{:}36 AM would set his new digital alarm clock for A:BC,A{:}BC, where A,A, B,B, and CC are digits. Find 100A+10B+C.100A + 10B + C.

Answer: 275
Concepts:clockunit conversionratio and proportion
Difficulty rating: 1820
Solution:

An ordinary day has 6024=144060 \cdot 24 = 1440 minutes, and 6:366{:}36 AM comes 660+36=3966 \cdot 60 + 36 = 396 minutes after midnight. A metric day has 10100=100010 \cdot 100 = 1000 metric minutes, so the equivalent metric time is 39614401000=275\frac{396}{1440} \cdot 1000 = 275 metric minutes after midnight, which the new clock displays as 2:75.2{:}75.

Therefore 100A+10B+C=275.100A + 10B + C = 275.

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