Time and Work

Problem Solving — algebra and arithmetic (GMAT Focus Edition)
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Time and Work

by eaakbari » Sun Apr 11, 2010 9:29 pm
I always seem to mess time and work problems up. Any insight?
Whether you think you can or can't, you're right.
- Henry Ford
Source: — Quantitative Reasoning |

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by harshavardhanc » Sun Apr 11, 2010 11:29 pm
eaakbari wrote:I always seem to mess time and work problems up. Any insight?
E,

I always like to use percentages in these sums/problems. I feel uncomfortable in working with fractions and hence, use percetances instead.

For e.g. if a problem says A can complete work in 10 days. B has twice A's efficiency. In how many days would the work be completed if they work together.

Instead of working with 1/10 and 1/5 , I see work done/day by A as 10% and work done/day by B as 20% and add these two, which gives me 30% of the work done in one day. Therefore, 100% can be completed in 10/3 days :)

a little practice would make it easier to tackle these problems.
Regards,
Harsha

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by eaakbari » Mon Apr 12, 2010 5:40 am
harshavardhanc wrote:
eaakbari wrote:I always seem to mess time and work problems up. Any insight?
E,

I always like to use percentages in these sums/problems. I feel uncomfortable in working with fractions and hence, use percetances instead.

For e.g. if a problem says A can complete work in 10 days. B has twice A's efficiency. In how many days would the work be completed if they work together.

Instead of working with 1/10 and 1/5 , I see work done/day by A as 10% and work done/day by B as 20% and add these two, which gives me 30% of the work done in one day. Therefore, 100% can be completed in 10/3 days :)

a little practice would make it easier to tackle these problems.
Hmmm, yes you definitely make it sound simpler, but that would only be for numbers like 5 and 10 right. Or do you use it for a number like 17 too.

Thanks a bunch
Whether you think you can or can't, you're right.
- Henry Ford

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by harshavardhanc » Mon Apr 12, 2010 5:45 am
eaakbari wrote:
harshavardhanc wrote:
eaakbari wrote:I always seem to mess time and work problems up. Any insight?
E,

I always like to use percentages in these sums/problems. I feel uncomfortable in working with fractions and hence, use percetances instead.

For e.g. if a problem says A can complete work in 10 days. B has twice A's efficiency. In how many days would the work be completed if they work together.

Instead of working with 1/10 and 1/5 , I see work done/day by A as 10% and work done/day by B as 20% and add these two, which gives me 30% of the work done in one day. Therefore, 100% can be completed in 10/3 days :)

a little practice would make it easier to tackle these problems.
Hmmm, yes you definitely make it sound simpler, but that would only be for numbers like 5 and 10 right. Or do you use it for a number like 17 too.

Thanks a bunch
ha ha! you apple-picked the best number in this universe!! ;)

don't worry ! numbers like 17 and 19 won't appear in the questions of time and work till the 750 level :)

However, you may have to learn the reciprocals of numbers till 12. that is 8.33%.
Regards,
Harsha

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by eaakbari » Mon Apr 12, 2010 5:50 am
Haha , yes actually I did :wink:
Your post in Pipe leak (https://www.beatthegmat.com/pipe-leak-t55955.html) made me realize you do use percentages quite elegantly. I shall give the method a try.
Thanks, your a rockstar

E
Whether you think you can or can't, you're right.
- Henry Ford