Timber!
If I perform a vertical cut to cut a log into 2 pieces, it will take me 5 minutes. How many minutes will it take if I have to cut it into 4 pieces using parallel vertical cuts?
The log and its parts are not moved during the entire process and the cuts are all parallel to each other.
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13 solutions
But what if I cut it like this instead?
g
It would take 10 minutes in this case. The question is hence ambiguous.
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Yes. We could because the problem didn't mention that the cuts couldn't intersect.
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bt it has been said that the logs were not moved and cut vertically......
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@Tanjil Mostafa – considering cutting time only, i believe the answer should be 10 anyway
there are two axes vertical to the log, one parallel to the ground and the other perpendicular to the ground, assuming u cut through the axis parallel to the ground one piece will be above the other then u can cut the axis perpendicular to the ground, 2 cuts=2*5=10
assuming u cut through the axes in the opposite order, u will have 2 pieces requiring 2 more cuts, however the cross sectional area is halved so the equation will be like 3 cuts=1 5+.5 5+.5*5=10
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@Mohamed Yossry – you are not cutting a cake as it will remain coherent while you continue your cutting process
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@Ahmed Obaiedallah – please elaborate, also what do you think the answer should be
There should have only one option either 10 or 15.
Even I second this answer.
It is said that the cuts are parallel and the way you have cut is perpendicular
Yea... You could cut it in a cross or stack the cut pieces on one another. The question is not clear. They have to rephrase this one.
It said using vertical cuts only.
I'm both sorry and thankful for our misunderstanding. Thank you for correcting me ^_^
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Hey!! What will the answer be?? 10 or 15?? I answered 10 but it was wrong.....
While the ambiguity is valid, the question does say a LOG of wood which leads us to believe that the cuts do not intersect in any way. This is debatable.
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No Revant Chopra, the word "LOG" does not in any way, shape, or form, lead anyone to think that the cuts somehow cannot intersect. There is absolutely no justification to make that assumption. And Matth Matth's proposition above is EXACTLY the way I also thought about it, which is the most time and energy efficient way to achieve the same result.
As for the question's ambiguity: it's actually even more ambiguous than mentioned above. The question is also not entirely clear as to whether the author(s) is/are asking for the overall time it would require, from the beginning of the initial cut until you have four pieces, or if he/she/they are asking how much time it would take to turn the initial cut and two pieces into four pieces (in which case, it would be either 5 minutes, or 10 minutes, depending on one's approach -- the efficient way that Matth Matth and I would take, or the inefficient way that you would take.) ;-p
Well, I just corrected my own problem. Well... sorry for that... He said that before I wrote the "should not intersect" point.
But the question says vertical cut. So, one of the lines in your figure is horizontal?
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No it's not! Horizontal would be cutting it sideways (i.e. from left to right, or right to left.) The vertical stipulation means from top to bottom, which this is still doing. This is just a question of whether it's parallel or perpendicular to our initial viewpoint -- that's different from a question of vertical cuts vs. those that are done side-ways.
Assume that it's a bird's eyes view
It is stated that the log is not moved during the cut. And the only kind of cut used is a vertical cut.
That is why it says, "vertical parallel cuts."
Even if this doesn't run into problems with the 'vertical' stipulation, it is totally dependent on how long the logs are. If the logs are longer than they are thick (which seems likely), it will take longer than 5 minutes to cut it this way.
It doesn't mean that cutting 2 pieces, you need 1 cut. We answered like this. pieces to minutes. so 2:5 = 4:n. So we are focused into how many pieces is cut, not into how many logs are being cut. So the answer must be 10
I too support you math math
I think you could fold it on itself and then cut it through thé layers resulting in only 2cuts
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This is true--the problem states the logs are not moved d u r i n g t h e c u t s ; this says nothing about moving the logs b e t w e e n the cuts.
But what if I can make 2 cuts together
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still ten minutes flip the one piece over so the cuts are not intersecting
That's really smart, but Mathh Mathh is right.
What if i cut it by combining the two pieces that I cut in the first cut. Then, I would require two cuts only. Example: the way we normally slice fruits or vegetables
when i can get 4 identical pieces in 10 min why to waste 5 min more. plz use ur brain whosoever has mention the ans as 15 min.
If we are cutting the log in 4 pieces and it is stated that the log does not move during cutting process then i think we can do it in just two cuts across the diameter....
Hi. Question never says we cannot cut on our previous cut. So I can cut 4pieces with 2cuts perpendicular to each other. I dont know why its 3cuts when 2 is possi
You can cut a log into 4 pieces with 2 cuts. I think the answer should be 10 minutes.
Sometimes you realize that you've already made a cut that took 5 minutes, and you're cutting the same log, being specified as "it". So you make your last two cuts in 10 minutes because who has the time to get a new log of the same size and density to cut 3 more times? Maybe I think too practically for these problems...
Yes. Let's use the logical part of our brain:
The log is already in two pieces. Cut each piece in half makes four pieces in 2 cuts. Each cut is 5 minutes. Total time 10 minutes.
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Is the assumption here, then, that the log is already cut?
I think the "if" statement at the beginning is meant to be a hypothetical reference, rather than a general introduction to the problem. Still, I can't say the read is not as valid as some of the others (since corrected in the problem text--thanks to the original author).
10 minutes ... if it is a square pc of wood ... one cut from left to right and another from top to bottom
, .. bad thinking,.. :D
Logically there are 2 good answers: 1) Take your time to cut 3 times: chop, move. Chop, move. Chop. Each cut is 5 minutes; 3*5=15 2) Cut length-wise, then width-wise. 2 cuts, 10 minutes 3) Cut normally, then line the two partial-logs up next to each other, cut both at same time. 2 cuts, 10 minutes.
Option 3 still does not involve intersecting cuts, but it is a lot more efficient unless you have some kind of logging machine or OCD
I guess option 2 is not acceptable.. coz it stated that vertical parallel cut..
All this question requires is a little extra attention to the details. The question says, "How many minutes will it take if I cut
it
into 4 pieces?" I emphasized on
it
because
it
indicates that we are dealing with only one log here.
Had the question been like,
"How many minutes will it take if I have to cut 4 pieces?"
,then the correct answer would have been
10 min
as we would have needed only 2 cuts on 2 different logs.
But, since the question deals with cutting the same log over and over, we need to make 3 cuts in order to divide the only log into two pieces which can be further divided into 4 pieces. So, the
it
in the question, is the reason that we need to make an extra cut.
"It" does imply a single log, correct; however, you can make two vertical cuts to achieve four end-pieces, but simply turning your second cut perpendicular to your viewpoint. This is still a vertical cut, but allows two cuts for four pieces, and a total of 10 minutes of required time.
Thank you for correcting me.
the second and third cut should take less than 5 mins each, the affected area is halved, less resistance on the cutting tool, definitely less than 15 and closer to 10
For 1 cut a log into two piece ,which takes 5 min. now to cut log into 4 pieces we need 3 cuts which will take 5*3=15 minutes. Answer in logical thinking.
the cuts are not identical though
Same with me pal. Just logical question
The given piece into two in 5 minutes. Again one of the two pieces we can cut into two in 5 minutes. Similarly the other also in 5 minutes. So 5 + 5 + 5 = 15 minutes
I agree with Jeremy about the ratio, but, an easier way to do it is use a piece of paper and imagine 4 cuts and multiply the amount by the number 5.... which is 3x5=15.
to cut a log into two pieces we need to make one cut,which takes 5 min. now to cut log into 4 pieces we need 3 cuts which will take 5*3=15 minutes..
length also comes under consideration how we can say to cut the wood take five minutes
To have two pieces, you must have one cut. To have four pieces you must have three cuts. We know that one cut lasts for 5 minutes. Therefore, the three cuts will last for ( 3 ) ( 5 ) = 1 5 minutes.
You cut it in half: 5 minutes You cut the 2 halves in half: 5 minutes per each half cut in half, resulting in 10 minutes... If you do just that, you will be left with 4 equal pieces. The amount of time it took to complete this task was 15 minutes
5 + 5 + 5 = 15
Given 1 cut requires 5 minutes . Therefore 3 cuts (1 cut - 2 pieces , Each of the two piece requires one cut each to cut each one of those into 2 pieces). Hence 1+1+1 = 3 cuts. One cut requires 5 minutes , 3 cuts require 5 . 3 = 15
4 pieces = 3 cuts ! 1 cut = 5 minutes , 3 cuts = 15 minutes !
For 2 cuts, 5 minutes are needed But, if we cut the third time , it is already in four pieces So, it give the answer-3*5=15
Actually it depends on which way you cut it.
Let's assume that the log is a uniform cylinder and that you are cutting it to make a circular cross section.
One cut will make two pieces.
Obviously three cuts will make 4 pieces.
You can either try and visualise it, or see that each cut adds a piece (kind of like the idea of there always being one less fence than there are posts, or for every break in a large piece of chocolate, you add a piece).
If one cut takes 5 minutes, three cuts will take 15 minutes.
So, with your perfectly cylindrical log, you make once cut in 5 minutes, splitting the log into two equal halves. With those two halves still positioned next to each other, you rotate 90 degrees and make another cut, through both halves simultaneously, creating 4 equal quarters of the original log. This would be the most efficient method, and would take only 10 minutes rather than 15.
Sometimes you need to use your logical side of your mind, since (I think) some of you do 2 : 5 = 4 : n ... Here's the solution:
To cut a log into 2 pieces, you only need ONE cut. And to cut a log into 4 pieces, you need 3 cuts. So the real ratio is:
1 : 5 = 3 : n
..which leaves an answer of 1 5 minutes