Measuring time without clocks.!

i have a very tricky kind of Question :

there are two of same length ropes,each burns in 1 hour.how could u measure 45 minutes with these two ropes?? U can neither cut the rope nor fold it.

Easy Math Editor

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`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
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Comments

You have ropes that behave in a similar manner, but they take 1024 seconds to burn. What is the minimum number of fuses you need to measure 1025 seconds.

Brock West - 8 years, 2 months ago

align the two ropes together fire the end of the first rope and the opposite end of the second rope fire goes in different directions in the two ropes after 30 minutes fires in both ropes meet each other

then pull one of the two ropes in the same direction as fire in the other rope

now:

fire goes in different directions once again wait till the fires meet each other (this happens after 15 minutes)

so u got 45 min :D

Abanoub Hanna - 8 years, 2 months ago

I remember reading the solution to this problem of a different variation ( It involves mosquito coils instead of rope), but I can't remember it. Let me just find it somewhere.

Alvin Jae Cabato - 8 years, 3 months ago

Now I remember: You set both ends of one rope on fire then one end of the other. The result is that your first rope ( which you lit both ends with fire) will burn for 30 mins. When your first rope is gone now and 30 mins elapsed, light the end of the other rope. Because the rope you lit at one end only, it has a life span of 30 mins. Lighting the other end makes it burn twice as fast making it last for 15 mins. When the 2nd rope is gone 45 mins passed.

In short, light both ends of one rope and one end of the other. When the one that was lit on both ends is gone, light the last end which has not been lit on fire. The end result is 45 minutes :)

Alvin Jae Cabato - 8 years, 3 months ago

yeah. thats it!

Ranjana Kasangeri - 8 years, 3 months ago

i did not understand what to do with 2nd rope

Varun Mangla - 8 years, 2 months ago

@Varun Mangla – You burn just one end of the 2nd rope along side the first rope. Once the first rope is gone/burnt all the way you light the unlit end of the rope

Alvin Jae Cabato - 8 years, 2 months ago

its to easy, follow tese steps 1. burn the first rope from both the ends n the 2nd rope from 1 end 2. when the first rope is fully burnt then burn the second ebd of the 2nd rope 3. the 2nd rope will burn fully the the time from startin till end is 45 mins

Keshav kumar - 8 years, 2 months ago

When three-fourth of the rope will be burnt, the time elapsed would be 45 minutes.

Sarthak Nandan - 8 years, 2 months ago

Take one rope ..... Fold it into equal four.... cut one of the quarters..... then start burning the other long one.... [Each quarter is 15 mins. A rope is 1 hour.... So, 1hour \ 15 mins is = 45 mins.... simple......]

Bharath Manikandan - 8 years, 2 months ago

u can neither cut nor fold the rope !

Rashmi B K - 8 years, 2 months ago

very easy . First Of All Let The Rope To Burn Upto Half It Means 30 minutes gone.Now Let The Rope To Burn Half Of The Remaining Half It Means 30/2 means 15..WHen this is complete it means u spend 45 minutes

Rana Shubham - 8 years, 2 months ago

Math	Appears as
Remember to wrap math in `\(` ... `\)` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$