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axisymmetric
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GMATprep Geometry question
This topic has expert replies
Source: Beat The GMAT — Problem Solving |
If you take each tick mark and break and find the lowest common denominator than put them in numerical order and you will quickly see 20/35 and 21/35 come up in the ordering which is the smallest space between the hash marks
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axisymmetric
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discreet
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I think we can generalize this....the Lowest distance should be the GCD\HCF of the two numbers 5 and 7 = 35...
So,lowest possible distance is 1/35....you can test it with any no. of options to satisfy yrself and then perform the test that drholmer has given
....eg: 2 and 5 parts , 6 and 7 parts, 3 and 4 parts etc etc 
So,lowest possible distance is 1/35....you can test it with any no. of options to satisfy yrself and then perform the test that drholmer has given
....eg: 2 and 5 parts , 6 and 7 parts, 3 and 4 parts etc etc The least possible distance can only be between the smaller tick mark (sevenths) and the longer tick mark (fifths). There is no trick in solving this, just use first principles. Start from zero, the distance between zero and the first seventh tick mark is 1/7. Similarly 1/5, from zero to the first fifth tick mark. Subtract 1/5 -1/7 = 2/35 is the answer
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gmattester
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Can someone verify this method...discreet wrote:I think we can generalize this....the Lowest distance should be the GCD\HCF of the two numbers 5 and 7 = 35...
So,lowest possible distance is 1/35....you can test it with any no. of options to satisfy yrself and then perform the test that drholmer has given
Or if someone has shorter method to solve this question with proper logic
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Ian Stewart
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It's not likely you'll see this exact type of question again, but the method is correct, although discreet surely means the LCM, not the GCD. I'll only prove it if someone asks, though; the proof is a bit abstract. On the GMAT, you would not be expected to know this kind of fact- for this question, it's easy enough to write down all of the fractions with a common denominator, 35:gmattester wrote:Can someone verify this method...discreet wrote:I think we can generalize this....the Lowest distance should be the GCD\HCF of the two numbers 5 and 7 = 35...
So,lowest possible distance is 1/35....you can test it with any no. of options to satisfy yrself and then perform the test that drholmer has given
Or if someone has shorter method to solve this question with proper logic
5/35, 7/35, 10/35, 14/35, 15/35, 20/35, 21/35, 25/35, 28/35, 30/35
and you can see all the possible distances that way.
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com
ianstewartgmat.com
ianstewartgmat.com
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gmattester
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Thanks Ian.....Ian Stewart wrote:It's not likely you'll see this exact type of question again, but the method is correct, although discreet surely means the LCM, not the GCD. I'll only prove it if someone asks, though; the proof is a bit abstract. On the GMAT, you would not be expected to know this kind of fact- for this question, it's easy enough to write down all of the fractions with a common denominator, 35:gmattester wrote:Can someone verify this method...discreet wrote:I think we can generalize this....the Lowest distance should be the GCD\HCF of the two numbers 5 and 7 = 35...
So,lowest possible distance is 1/35....you can test it with any no. of options to satisfy yrself and then perform the test that drholmer has given
Or if someone has shorter method to solve this question with proper logic
5/35, 7/35, 10/35, 14/35, 15/35, 20/35, 21/35, 25/35, 28/35, 30/35
and you can see all the possible distances that way.
Much clear now.
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mehravikas
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I have been preparing for GMAT and I have finished OG, Kaplan, PR. I just gave a GMAT prep yesterday, and to be honest could get only 21 questions correct in quant. I have always scored more than 80% on all the gmat practice material. But I guess Gmat prep is entierly different from Kaplan (way too tough), PR and OG (too easy).
Would you recommend more practice to these kind of questions or some other material???
Would you recommend more practice to these kind of questions or some other material???
gmattester wrote:Thanks Ian.....Ian Stewart wrote:It's not likely you'll see this exact type of question again, but the method is correct, although discreet surely means the LCM, not the GCD. I'll only prove it if someone asks, though; the proof is a bit abstract. On the GMAT, you would not be expected to know this kind of fact- for this question, it's easy enough to write down all of the fractions with a common denominator, 35:gmattester wrote:Can someone verify this method...discreet wrote:I think we can generalize this....the Lowest distance should be the GCD\HCF of the two numbers 5 and 7 = 35...
So,lowest possible distance is 1/35....you can test it with any no. of options to satisfy yrself and then perform the test that drholmer has given
Or if someone has shorter method to solve this question with proper logic
5/35, 7/35, 10/35, 14/35, 15/35, 20/35, 21/35, 25/35, 28/35, 30/35
and you can see all the possible distances that way.
Much clear now.
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sudhir3127
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Request you to please post ur question on an appropriate thread.. i am sure u will get the answers quickly and in more organised way...mehravikas wrote:I have been preparing for GMAT and I have finished OG, Kaplan, PR. I just gave a GMAT prep yesterday, and to be honest could get only 21 questions correct in quant. I have always scored more than 80% on all the gmat practice material. But I guess Gmat prep is entierly different from Kaplan (way too tough), PR and OG (too easy).
Would you recommend more practice to these kind of questions or some other material???
gmattester wrote:Thanks Ian.....Ian Stewart wrote:It's not likely you'll see this exact type of question again, but the method is correct, although discreet surely means the LCM, not the GCD. I'll only prove it if someone asks, though; the proof is a bit abstract. On the GMAT, you would not be expected to know this kind of fact- for this question, it's easy enough to write down all of the fractions with a common denominator, 35:gmattester wrote:Can someone verify this method...discreet wrote:I think we can generalize this....the Lowest distance should be the GCD\HCF of the two numbers 5 and 7 = 35...
So,lowest possible distance is 1/35....you can test it with any no. of options to satisfy yrself and then perform the test that drholmer has given
Or if someone has shorter method to solve this question with proper logic
5/35, 7/35, 10/35, 14/35, 15/35, 20/35, 21/35, 25/35, 28/35, 30/35
and you can see all the possible distances that way.
Much clear now.
thanks
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mehravikas
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Thanks Sudhir. You can view my thread on https://www.beatthegmat.com/help-needed- ... 16976.html
sudhir3127 wrote:Request you to please post ur question on an appropriate thread.. i am sure u will get the answers quickly and in more organised way...mehravikas wrote:I have been preparing for GMAT and I have finished OG, Kaplan, PR. I just gave a GMAT prep yesterday, and to be honest could get only 21 questions correct in quant. I have always scored more than 80% on all the gmat practice material. But I guess Gmat prep is entierly different from Kaplan (way too tough), PR and OG (too easy).
Would you recommend more practice to these kind of questions or some other material???
gmattester wrote:Thanks Ian.....Ian Stewart wrote:It's not likely you'll see this exact type of question again, but the method is correct, although discreet surely means the LCM, not the GCD. I'll only prove it if someone asks, though; the proof is a bit abstract. On the GMAT, you would not be expected to know this kind of fact- for this question, it's easy enough to write down all of the fractions with a common denominator, 35:gmattester wrote:Can someone verify this method...discreet wrote:I think we can generalize this....the Lowest distance should be the GCD\HCF of the two numbers 5 and 7 = 35...
So,lowest possible distance is 1/35....you can test it with any no. of options to satisfy yrself and then perform the test that drholmer has given
Or if someone has shorter method to solve this question with proper logic
5/35, 7/35, 10/35, 14/35, 15/35, 20/35, 21/35, 25/35, 28/35, 30/35
and you can see all the possible distances that way.
Much clear now.
thanks
