Mario's watch runs fast. In one day, it gains an hour. So in twelve days it gains 12 hours and is correct again. Julio's watch also runs fast. In one day it gains twenty minutes. Suppose they both set their 12 hour watches correctly at 9:00 a. m. on Monday. When will their watches next show the correct time together.

Question

Mathematics

Graham

30 April, 22:47

Mario's watch runs fast. In one day, it gains an hour. So in twelve days it gains 12 hours and is correct again. Julio's watch also runs fast. In one day it gains twenty minutes. Suppose they both set their 12 hour watches correctly at 9:00 a. m. on Monday. When will their watches next show the correct time together.

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Answers (1)

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Shawn · Answer 1

It takes Julio three times as long to gain as much extra time as Mario. So every 12 days Mario's click starts over at 9am. In 12 days, Julio will have only gained 4 hours. Julio needs to go 36 days to gain 12 hours. After 36 days both will be back at 9 am.