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Linear logic

by Mathsbuddy » Sat Nov 16, 2013 3:45 pm
A ladder 2 metres long is attached to the side of a boat sitting in a calm lake. The ladder has rungs 40cm apart and the water surface is exactly halfway up the ladder. If the tide raises the water at a constant rate of 20cm per hour, how long will it take before the top rung is totally submerged.

A) 5 minutes
B) exactly 5 hours
C) just over 5 hours
D) just under 5 hours
E) none of the above
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by Brent@GMATPrepNow » Sat Nov 16, 2013 3:59 pm
Mathsbuddy wrote:A ladder 2 metres long is attached to the side of a boat sitting in a calm lake. The ladder has rungs 40cm apart and the water surface is exactly halfway up the ladder. If the tide raises the water at a constant rate of 20cm per hour, how long will it take before the top rung is totally submerged.

A) 5 minutes
B) exactly 5 hours
C) just over 5 hours
D) just under 5 hours
E) none of the above
This kind of trick question would never appear on the GMAT.

Solution: [spoiler]Since the ladder is attached to the boat, it will rise as the boat rises. So, the water will always be half submerged.
[/spoiler]

Cheers,
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by [email protected] » Sat Nov 16, 2013 6:59 pm
Hi Mathsbuddy,

Brent is absolutely correct. This isn't a GMAT question; seems more like a question that might show up in a High School Physics Quiz. What is the source of this question?

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by sanju09 » Sun Nov 17, 2013 1:02 am
Mathsbuddy wrote:A ladder 2 metres long is attached to the side of a boat sitting in a calm lake. The ladder has rungs 40cm apart and the water surface is exactly halfway up the ladder. If the tide raises the water at a constant rate of 20cm per hour, how long will it take before the top rung is totally submerged.

A) 5 minutes
B) exactly 5 hours
C) just over 5 hours
D) just under 5 hours
E) none of the above
Serious GMAT aspirants may please ignore this thread. I request Mathsbuddy to mention source of the questions he kindly posts. The wordings of this question are openly very unlike to GMAT, and it sounds ambiguous at many places. Lots of assumptions to be made, and overall, if the water rises, so does the boat. What is there in this question then?
The mind is everything. What you think you become. -Lord Buddha



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by Mathsbuddy » Sun Nov 17, 2013 1:40 am
sanju09 wrote:
Mathsbuddy wrote:A ladder 2 metres long is attached to the side of a boat sitting in a calm lake. The ladder has rungs 40cm apart and the water surface is exactly halfway up the ladder. If the tide raises the water at a constant rate of 20cm per hour, how long will it take before the top rung is totally submerged.

A) 5 minutes
B) exactly 5 hours
C) just over 5 hours
D) just under 5 hours
E) none of the above
Serious GMAT aspirants may please ignore this thread. I request Mathsbuddy to mention source of the questions he kindly posts. The wordings of this question are openly very unlike to GMAT, and it sounds ambiguous at many places. Lots of assumptions to be made, and overall, if the water rises, so does the boat. What is there in this question then?
Having responded to so many other people's threads I thought it only fair to a make a contribution. Sorry, I should have said it was made up and loosely based on a question I heard a long time ago. It was an attempt to make a question that tested a person reading the question properly, and which challenged a person into not making assumptions. These are 2 key skills required of any GMat question. Yes, it would rise with the boat, so answer D. Well done. .
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by sanju09 » Sun Nov 17, 2013 2:41 am
Mathsbuddy wrote:
sanju09 wrote:
Mathsbuddy wrote:A ladder 2 metres long is attached to the side of a boat sitting in a calm lake. The ladder has rungs 40cm apart and the water surface is exactly halfway up the ladder. If the tide raises the water at a constant rate of 20cm per hour, how long will it take before the top rung is totally submerged.

A) 5 minutes
B) exactly 5 hours
C) just over 5 hours
D) just under 5 hours
E) none of the above
Serious GMAT aspirants may please ignore this thread. I request Mathsbuddy to mention source of the questions he kindly posts. The wordings of this question are openly very unlike to GMAT, and it sounds ambiguous at many places. Lots of assumptions to be made, and overall, if the water rises, so does the boat. What is there in this question then?
Having responded to so many other people's threads I thought it only fair to a make a contribution. Sorry, I should have said it was made up and loosely based on a question I heard a long time ago. It was an attempt to make a question that tested a person reading the question properly, and which challenged a person into not making assumptions. These are 2 key skills required of any GMat question. Yes, it would rise with the boat, so answer D. Well done. .
I am sorry if it hurt you, my aim was just to alert our visitors. You are always welcome to post anything which is of some interest to our visitors.

[spoiler]By the way, if it would rise with the boat, how the answer is D, why not E? [/spoiler]
The mind is everything. What you think you become. -Lord Buddha



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by sanju09 » Sun Nov 17, 2013 3:07 am
Brent@GMATPrepNow wrote:
Mathsbuddy wrote:A ladder 2 metres long is attached to the side of a boat sitting in a calm lake. The ladder has rungs 40cm apart and the water surface is exactly halfway up the ladder. If the tide raises the water at a constant rate of 20cm per hour, how long will it take before the top rung is totally submerged.

A) 5 minutes
B) exactly 5 hours
C) just over 5 hours
D) just under 5 hours
E) none of the above
This kind of trick question would never appear on the GMAT.

Solution: [spoiler]Since the ladder is attached to the boat, it will rise as the boat rises. So, the water will always be half submerged.
[/spoiler]

Cheers,
Brent
Hi Brent,

[spoiler]I am sure you meant ladder not water, in the bold part of yours. Otherwise water would get wet.[/spoiler]
The mind is everything. What you think you become. -Lord Buddha



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by Mathsbuddy » Sun Nov 17, 2013 4:29 am
sanju09 wrote:
Mathsbuddy wrote:
sanju09 wrote:
Mathsbuddy wrote:A ladder 2 metres long is attached to the side of a boat sitting in a calm lake. The ladder has rungs 40cm apart and the water surface is exactly halfway up the ladder. If the tide raises the water at a constant rate of 20cm per hour, how long will it take before the top rung is totally submerged.

A) 5 minutes
B) exactly 5 hours
C) just over 5 hours
D) just under 5 hours
E) none of the above
Serious GMAT aspirants may please ignore this thread. I request Mathsbuddy to mention source of the questions he kindly posts. The wordings of this question are openly very unlike to GMAT, and it sounds ambiguous at many places. Lots of assumptions to be made, and overall, if the water rises, so does the boat. What is there in this question then?
Having responded to so many other people's threads I thought it only fair to a make a contribution. Sorry, I should have said it was made up and loosely based on a question I heard a long time ago. It was an attempt to make a question that tested a person reading the question properly, and which challenged a person into not making assumptions. These are 2 key skills required of any GMat question. Yes, it would rise with the boat, so answer D. Well done. .
I am sorry if it hurt you, my aim was just to alert our visitors. You are always welcome to post anything which is of some interest to our visitors.

[spoiler]By the way, if it would rise with the boat, how the answer is D, why not E? [/spoiler]
Indeed. Thank you for spotting my typo. May it be a lesson to all to type in the right answer too! :)
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