Grannie’s watch gains 30 minutes every hour, whilst Grandpa’s watch loses 30 minutes every hour. At midnight, they both set their watches to the correct time of 12 o’clock. What is the correct time when their two watches next agree?
Select one option, then click Submit.
6am
9am
12 noon
3pm
6pm
Select an option, then submit.
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Intermediate Mathematical Challenge 2007 (2007)
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