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, 2012

Combinatorics Difficulty 1.5 Junior Find the answer Canada

Yelena recites $P, Q, R, S, T, U$ repeatedly (e.g. $P, Q, R, S, T, U, P, Q, R, \dots$ ). Zeno recites $1, 2, 3, 4$ repeatedly (e.g. $1, 2, 3, 4, 1, 2, \dots$ ). If Yelena and Zeno begin at the same time and recite at the same rate, which combination will not be said?

Pick one

Solution

Since 1 mm of snow falls every 6 minutes, then 10 mm will fall every $6\times10=60$ minutes.

Since 10 mm is 1 cm and 60 minutes is 1 hour, then 1 cm of snow will fall every 1 hour.
Since 1 cm of snow falls every 1 hour, then 100 cm will fall every $1\times100=100$ hours.

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