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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.

12
votes
3answers
290 views

You cannot have 120 degrees of separation, but how close can you get?

If you take a look at a standard three-hand gear-driven analog clock, there is never(see footnote) a time of day where the hands of the clock divide the face equally into 120 degree segments, but you ...
52
votes
12answers
10k views

A clock correct three times a day

A stopped clock tells the right time twice a day. How fast must a clock go for it to be right three times a day?
10
votes
4answers
577 views

Short Puzzle: Graphic Painting

The artist in the market is giving this painting for free (the last one on his rack). I asked him if I can take it but he replied "Why should I give it to you?" The frame could be useful but I dont ...
5
votes
5answers
399 views

Time-Motion puzzle

Time and Motion studies are well established. Here is an easy question: It takes 8 men 6 months to build 2 houses at a cost of $50,000. It takes 10 men 5 months to build 3 houses at a cost of ...
23
votes
3answers
2k views

Digital Clock Brightness

My alarm clock has a typical 7-segment digital display showing hours and minutes. Every lit segment is equally bright, and every unlit segment is equally dark. The separator (:) is always lit. ...
10
votes
4answers
515 views

Mirrored clocks

Triangulating for the simplest puzzle that is still at least somewhat interesting to solve.. On the left side wall in this picture, we have two particular clocks: 1: an analog clock with identical ...
4
votes
2answers
743 views

What timezone am I?

It was 17:52 in the evening and I couldn’t wait for my class to finish. Only 8 more minutes… I really hate night school! I sat there pondering the stuff on the blackboard and wondering why he wrote ...
4
votes
2answers
225 views

Switching the clock

"Observe the time, would you, Watson, old chap?" I did as instructed and glanced at the large grandfather clock standing in the corner. "Just a little after 4.42, Holmes." He nodded, "So when the ...
2
votes
2answers
201 views

What are the chances on watching the clock? [closed]

This is a relatively straightforward little puzzle, but the answers are somewhat unintuitive or can prompt a new perspective. It might be an interesting little puzzle for a probability teaching ...
-7
votes
5answers
180 views

cowboy rodeo riddle [closed]

First, the cowboy went to the rodeo on Monday. Three days later, he went back home on Friday. Can you solve it?
17
votes
14answers
11k views

My birthday is uncommon

I was born 1 day after my sibling. Yesterday was my sibling's birthday but today is not my birthday. When is my birthday?
29
votes
11answers
12k views

Born on the same day, but one is two years older

Two people were born on the same day, same year, and share the same birthday. One is 2 years old, the other is only a few days old. What's going on here?
9
votes
2answers
269 views

Where are you at this time

Where are you if, When it's 10 o'clock, it's 2 o'clock When it's 5 o'clock, it's 7 o'clock
7
votes
2answers
327 views

How many dates are ambiguous across the Atlantic?

The Day/Month/Year date system commonly used in Britain (and much of Europe?) and the Month/Day/Year system commonly used in the US can lead to confusion when, for example, we write 9/3/2018 for the ...
19
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 ...
10
votes
4answers
574 views

How to rephrase this puzzle about a meditating monk and incense

Here's a math-flavored puzzle I found on Andrej Cherkaev's website that I like to give to my undergraduate math students. I've paraphrased it to try to make it clearer: A monk was instructed by his ...
3
votes
5answers
581 views

Curiosity of February 5$^{th}$

Some people write February 5$^{th}$ using the md format, as $2.5$ or alternatively as $2/5$. Note that $2.5 \times \frac25 = 1$. Is there any other date satisfying $a.b \times \frac{a}{b} = 1$? ...
8
votes
2answers
471 views

A Final Twins Puzzle: Twelve Days Difference?

Inspired by @athin's One More Twin Puzzle: Four Days Difference? After reading @athin's question, I was inspired to ask my own puzzle club about their birthdays. One of the members, Ethan, surprised ...
13
votes
3answers
768 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 ...
11
votes
2answers
413 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 ...
15
votes
2answers
431 views

“Musical chair” for clock hands

A colleague and me usually make bets on the time when a simulation is finished. Next time I would suggest the following: At the time the simulation is finished we take a look at the analog clock on ...
7
votes
1answer
217 views

What is it this Time?

Most clocks tell the time, but some are for letters. ...
11
votes
5answers
3k views

This puzzle is late!

I meant to release this puzzle 15¼ hours ago, and forgot again just over 9⅓ hours ago. But don't worry, it's fine. The puzzle is finally out. What is this puzzle about? NB: What timezone I am ...
15
votes
1answer
2k views

Finally, you wake up from a coma

You can barely open your eyes when a doctor walks up to you: You are a lucky one. Not many people have survived an accident like this. Only a handful of neurosurgeons are able to perform such an ...
-3
votes
1answer
90 views

Daylight And Standard Time Not Equal Timespan Yet Works Out [closed]

I have been thinking about this for a long time now, and no one can answer it. I forget the exact length span, however, the span for each is not equal. For example, DST is 120 days, and "standard" ...
6
votes
7answers
12k 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?
35
votes
5answers
8k views

Measure 22 minutes with 7 and 13 minute hourglasses

You have two hourglass timers. One can measure 7 minutes and the other hourglass timer can measure 13 minutes. This means that it takes 7 minutes for the sand timer to completely empty the sand from ...
6
votes
7answers
3k views

Full-sized ice cubes

On a table in front of you is a small freezer that is capable of holding seven standard ice cube trays stacked on top of each other. There are no shelves to separate the trays, and if you stack one ...
4
votes
3answers
381 views

The time is approximately 10:10

Watches in advertisements tend to be set to 10:10 (unless you're Apple). The reason seems to be that the hands are symmetrical when they're at 10:10. Except they're not. The hour hand moves ...
4
votes
8answers
5k views

How many minutes is it before 12 noon? (tricky)

This puzzle is a one I met in an IQ test. I believe it's so tricky, however, the concept is quite simple. How many minutes is it before 12 noon if 68 minutes ago it was three times as many minutes ...
1
vote
2answers
210 views

X past X, Y to Y

While sitting in the waiting hall a wall clock caught my attention. I realise there are only 15 minutes left for the conversation that will determine my path in life. I then took a glance at my watch. ...
7
votes
5answers
696 views

One a puzzle, two a puzzle, Hot Cross Clocks

It's Good Friday! I want to make perfect hot cross buns by superimposing two 12-hour clock faces on top of each other. Is this possible, and if so, how many ways are there of doing so? In other ...
13
votes
5answers
3k views

How often does a digital watch show a palindrome?

A palindrome is a word, phrase, number, or other sequence of characters which reads the same backward or forward, such as madam or kayak. We have a digital watch showing the time HH:MM:SS as shown in ...
17
votes
3answers
2k views

Two brothers, two watches

Two brothers, Jack and Joe, were born in May. One was born in 1932, and the other, a year later. Each brother owned a watch, which was previously possessed by their father. Considering their age, ...
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., ...
5
votes
1answer
883 views

A time-traveller's puzzle

Intense and long story coming up... In a galaxy, far, far away there lived a population of creatures, human-like but definitely smarter. The whole galaxy experienced three phases for every Earth ...
-3
votes
1answer
340 views

Two burning ropes measure 5 minutes

Today I was at a job interview and the last question was, "How can I measure 5 minutes by lighting two ropes that each take an hour to burn but do not burn uniformly?" (classical). I know how to ...
17
votes
6answers
4k views

A weird and spooky clock

Out of nowhere, a clock appeared on my desktop: (you don't have to be able to view the GIF in order to solve it, I think the "preview" image gives you all the minor clues hidden in it. I also ...
3
votes
2answers
348 views

Digital Alarm Clock

Most of the alarm clock's bulbs are busted as shown above in black shades. Although still working it is not possible to tell what time is it. If we can fix it to display a pattern every seconds, ...
11
votes
2answers
2k views

When was I born?

I was born just 10 minutes apart from my twin brother, but I celebrated my birthday 11 days after my twin brother every year. When was I born ?
-1
votes
2answers
155 views

Speeding up half way [duplicate]

On my way to the supermarket, I walk at a certain speed. I want my average speed for the back and forth trip to be twice that speed. At what speed should I go back home to reach that goal?
-3
votes
3answers
192 views

How to restore the scrambled master clock? [closed]

I don't know how the master clock, with which other clocks in the world are synchronized, is setup. who decided the mechanism used to setup the master clock when the master clock was setup how to ...
1
vote
4answers
436 views

Clock time Puzzle

What will be the time when the hour, minute, and second hands will all coincide in between 6 O'Clock and 7 O'Clock? How should I approach this type of question? Can anyone explain it?
3
votes
3answers
584 views

What should be 'the next time'?

A question was asked in a mental ability test (which ended on Saturday). What comes next in this pattern of time: 2:25, 4:34, 1:57, 6:16, ___ Note: 1. No extra information is given like 12/24 ...
9
votes
2answers
351 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 ...
2
votes
3answers
181 views

What happened there between Alice and Bob

So our favourite couple, Alice and Bob finally decided to get married ;) Bob was already working in a well reputed company as Information Security Analyst. Alice, used to get bored at home, so she ...
2
votes
3answers
563 views

The poorly designed clock [duplicate]

I gave a mental ability test today in which this question was asked. The hour and minute hands of a clock are indistinguishable. How many minutes are there in a day (24 hours) when it is not ...
9
votes
6answers
2k views

A mosquito is born at T=0 and after 2 seconds makes a new mosquito every second, how many mosquitos at T=8.5? [closed]

One mosquito is born at T=0 and after 2 seconds it makes a new mosquito, and another every second thereafter. All such mosquitoes have this same property and do not die. How many mosquitoes there are ...
2
votes
3answers
143 views

Safety Fuses and Matches [duplicate]

You have 2 safety fuses and 4 matches. Each fuse takes exactly one hour to burn, but they are not perfect so may not necessarily burn evenly from both sides. For example, the first half might burn in ...
12
votes
3answers
784 views

Day and night of the two timers

            Make a non - 24 - hour day /  night cycle       &...