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.
15
questions
42
votes
5answers
6k 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....
8
votes
3answers
765 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 ...
8
votes
3answers
572 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 ...
33
votes
16answers
12k 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
19k 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
942 views
9
votes
2answers
381 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
5answers
20k 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 ...
5
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 ...
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., ...
22
votes
1answer
1k views
Aging A Lot Faster
The day before yesterday, I was 20 years old, and next year I will turn 23. What day is it today?
Note: This is not lateral-thinking, and the solution is real and ...
11
votes
2answers
485 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 ...
4
votes
1answer
507 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
910 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 ...
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?
