Brain Teasers
Two Clocks 2
At midnight on Sunday, December 31st, Professor Lawrence set two of her analog clocks to the correct time. One of her clocks gains one minute every hour and the other loses two minutes every hour.
1. When will the clocks next show the same time as each other?
2. When will the clocks both show the correct time?
1. When will the clocks next show the same time as each other?
2. When will the clocks both show the correct time?
Answer
1. Midnight after 10 days, which is 240 hours later. They both show 4 o'clock, one clock has gained 240 minutes (4 hours) and the other has lost 480 minutes (8 hours).2. Midnight after 30 days, which is 720 hours later. They both now show 12 o'clock.
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Comments
more of a math teaser than a riddle, but a good math teaser nonetheless
Thank you this is the first teaser that I got submitted here!
Good Job Kalli on your first teaser!!!
Well you sure gave us a hard one to start with. Thanks!
this was quite hard. Very good one.
Didn't find it particularly difficult, but very good teaser. Well done.
I don't see the difficulty here. The clocks take 60/(1+2) = 20 hours to have the minutes agree, at wguch time the hours differ by one, so in 20 x 12/1 = 240 hours both the hours and minutes will agree. Every 1+2=3 times they agree, the minutes will be zero and the time correct.
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