Problem 2 · 2010 Math Kangaroo
Easy
Logic & Word Problems
off-by-one
A 40 minute long lesson began at 11:50. Exactly in the middle of the lesson a bird flew into the classroom. At what time did this happen?
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Answer: C — 12:10
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Hint 1 of 2
"Exactly in the middle" of a 40-minute lesson is 20 minutes after it starts.
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Hint 2 of 2
Add half the length to the start time.
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Approach: add half the lesson length to the start
- Half of 40 minutes is 20 minutes.
- Start 11:50, then 20 minutes later is 12:10.
- So the bird flew in at 12:10.
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