Questions tagged [time]
Puzzles which include the concept of time, as for instance: clocks, dates, calendars, conversions from one time zone to another, time-intervals.
38
votes
5answers
5k views
Burning ropes as timers
You have 2 identical ropes which burn at a specific rate, and an unlimited supply of matches. When you light one end of a rope, the fire will take exactly 1 hour to travel to the other end of the rope....
32
votes
16answers
11k views
Older twin's birthday is one day after younger's
I have been asked this puzzle in an interview. There was not a lot of time left so I couldn't solve it quickly and the interviewer kind of let it go as he had to wrap up the interview
Foo and Bar ...
6
votes
7answers
16k views
A man is born in 1955
(I heard this in a movie and I think it’s pretty cool.)
A man is born in 1955. Today, the 14th of August, 2017, he is 18. How is this possible?
12
votes
3answers
810 views
7
votes
3answers
733 views
Odd hours with two timers
Two motorized 24-hour
light timers
are daisy
chained
between a power outlet and a light bulb.
For these timers, devise schedules and choose initial times
that produce the following repeated 9-hour ...
9
votes
2answers
358 views
Third timer's a charm
Three motorized 24-hour
light timers
are arranged between a power outlet and a light bulb,
with timer A parallel to a daisy
chain
of timers B and C.
For these timers, devise schedules
that ...
8
votes
3answers
538 views
Halve time with two timers
Two motorized 24-hour
light timers
are daisy
chained
between a power outlet and a light bulb.
For these timers, devise schedules and choose initial times
that produce the following repeated lighting ...
7
votes
5answers
15k views
Meeting of hands on a clock
We have a regular analog clock with three hands - second, minute and hour. On a given day, how many times do:
(a) the minute and hour hands
(b) the minute and second hands
(c) the hour and second ...
9
votes
3answers
2k views
Missed appointment
The story
This story occurs not far from Liège, in Belgium.
We are January 1st, 2013. Two bad men prepare the attack of a train. To do this, they set an appointment, during the year, at 2:30 a.m., ...
11
votes
2answers
445 views
Another Twin Puzzle: Three Days Difference
Today is my first day joining my college's Puzzle Club. It is so much fun gathering in a group with similar interests! I meet a lot of new friends and of course asked their contact number to discuss ...
6
votes
6answers
3k views
Timepieces and Moving Parts
The sundial keeps time with the fewest number of moving parts.
Which timepiece has the most moving parts?
4
votes
4answers
2k views
An Hourglass Puzzle
This puzzle follows from the well known sand timer puzzles:
A Sand Timer Challenge
http://www.crazyforcode.com/sand-timer-puzzle/
http://www.cut-the-knot.org/hg_solution.shtml
Warmup:
You are given a ...
4
votes
1answer
488 views
Connecting 3 circular power timers to lights so that they turn for one day on Christmas
My friend gave a question to me. I am not sure if it is an original puzzle, but he has 2 lines of Christmas lights and 3 circular timers with 96 switches apiece. Each switch turns on power for 15 ...
13
votes
3answers
832 views
One More Twin Puzzle: Four Days Difference?
This is updated version for Another Twin Puzzle: Three Days Difference
Today is my first day joining my college's Puzzle Club. It is so much fun gathering in a group with similar interests! I meet a ...
