solve dis puzzle

[bhavna04]

There are no time keeping mechanisms (watch, clock) in a room. There are 2 candles in the same room. Each candle when lit, has its wax completely exhausted in exactly 1 hour. How will you track the passage of 45 minutes? plzz help....:(

[cwarn23]

Simple. Only takes one candle.
Stand one candle up but don't light it and wait until the shadow has rotated 3.75 degrees anti-clockwise provided the room has a window. After the shadow has rotated the full 3.75 degrees then 15mins of daylight has passed. If you want 45mins then you will need to wait for it to rotate 11.25 degrees anti-clockwise. You can do that with any object and not just a candle. Now that's what I call a macgysmo aka Macgyver. I miss you Macgyver.

PS
If the room doesn't have a window use a candle to burn a hole in the wall to make a window.

[crunchie]

Now, how to figure 3.75 degrees.

[cwarn23]

Now, how to figure 3.75 degrees.

That can be determined by one of those circular rulers that show the number of degrees.

[Dani]

There are no time tracking devices in the room, but no one said there's no ruler in the room. Take a ruler and measure the candle, and you'll know how much needs to be burned for 45 mins.

[crunchie]

That is provided the candle burns at a constant rate :)

[BitBlt]

Break one of the candles in half, then break one of the halves in half again. You now have a quarter-candle.

Now light the whole candle, burn it until it is the same size as the quarter-candle.

This assumes, of course, that there are MATCHES in the room.

Just sayin... :icon_redface:

[VernonDozier]

You need the ruler to break the candle in two. If you have the ruler, then Dani's solution has it covered.

All these solutions only need ONE candle, yet we have two of them. Is the second candle a red herring? I think we can assume we have matches. Not so sure about the ruler. If we have a ruler, which both Dani and cwarn need in their solutions, I think Dani's is easier. No need to track shadows, no need to burn a hole in the wall. Might be about time for the OP to weigh in again?

EDIT --> "All these solutions only need ONE candle". Correction. Bit Bit's solution uses both.

[BitBlt]

Okay, okay, here goes...

Light one candle, and at the same time light the other candle at BOTH ENDS! Then when the second candle is consumed (after 1/2 hour), light the FIRST candle at its OTHER end...burns for 15 more minutes! 45 minutes on the dot!

Again, assumes that there are matches...also assumes you can light the candle at both ends and the wax is consumed at the same rate.

[Netcode]

Hmmmm! this is really brainstorming. I googled and here is what i found. Actually, this would aslo be possible if there is a window in the room at least.

[WaltP]

Now, how to figure 3.75 degrees.

Easy. Draw a circle. Take away everything that isn't 3.75 degrees.

[scudzilla]

Light 1 candle at both ends (assuming both ends have a wick exposed) and the other only at one end. Once the first candle burns out, 30 mins have passed and the second candle has 30 mins left. At that point, light the other end of the second candle.

Problem is, if both have only one end with a wick exposed you probably have to cut a piece from the other end, exposing the wick yourself and taking a few minutes total out of their lives :|

[susheelsundar]

i think 3/4 Candle is 45 mins?

[pritha.aash.7]

any1's nay idea?it's tricky

[BigPaw]

Lay one candle across the other (like a See-saw) until it balances - now you have measured the middle of the candle, halfway = 30 minutes. Make a very clear mark in the candle with your finger nail.

When the candle has burned down to your mark, and you can keep the candle burning as you do this, once again lay that candle across the other candle. (like a See-saw) When it balances evenly again you now mark that mid point clearly with your finger nail. You have now identified your remaining 15 minutes.

When the candle has burned down to your final mark, the candle has been burning for 45 minutes.

Verdicts?

[VernonDozier]

Seems like you have solved the problem of whether there is a ruler (you've found the midpoints without one). You also seem to have solved the problem of possibly not having wicks at both ends. Well done.

[kemcar]

You have to wait till the candle is burnt 3/4 th of its entire length, that will give you 45 mins.

[Reverend Jim]

False assumption. You all assume the candles burn at an even rate. They would not if they were tapered candles. Also, a candle will burn faster when turned horizontally as the wax will melt and drip off rather than burn.

[BigPaw]

Jim... :)

The question...

There are no time keeping mechanisms (watch, clock) in a room. There are 2 candles in the same room. Each candle when lit, has its wax completely exhausted in exactly 1 hour. How will you track the passage of 45 minutes? plzz help....:(

You said...

You all assume the candles burn at an even rate.

The question indicates...

Each candle when lit, has its wax completely exhausted in exactly 1 hour.

So, each candle lasts an hour.

You sound like you would be good at creating really challenging thinking problems. Why not give it a go?

[Reverend Jim]

I'm not good at creating puzzles but I love to solve them.

The question states that each candle burns completely in one hour. That doesn't mean that after half an hour the candle is half gone. If the candle is wider at the bottom than the top, it could take 20 minutes to burn through half its height and 40 minutes to burn the remainder.

[deceptikon]

The question states that each candle burns completely in one hour. That doesn't mean that after half an hour the candle is half gone. If the candle is wider at the bottom than the top, it could take 20 minutes to burn through half its height and 40 minutes to burn the remainder.

Unfortunately, this kind of overthinking is detrimental to finding an answer. Rather than approach it from the most complex way possible, you should simplify through reasonable assumptions. That way the problem can be solved in a consistent state and confounding variables may be added as necessary.

This question is actually pretty old, and yes, you're allowed to assume that the candles all burn uniformly from beginning to end.

[Reverend Jim]

That was an extreme case of making a false assumption and I suggested it to (perhaps badly) make a point. I think It is valid to assume that turning a candle horizontally will make it burn faster. in that case, the solution os to cut the candles in two and burn them vertically. You can find the midpoint by placing the candle horizontally on your index fingers (one at each end) then slowly moving your fingers together. The candle will stay balanced. Your fingers will meet at the midpoint.