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Is calculation the only way?

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mwilliams82
 Post subject: Is calculation the only way?
 Post Posted: Thu Sep 03, 2009 10:26 pm 
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Students


Posts: 8
The more I study the gmat the more obsessed I've become with finding out how to find answers w/o calculation. I know how to calculate such problems as the following but have realized calculation is often the number one culprit that derails my timing and causes careless errors. SO, can the following problem be solved by ball-parking or abstract logic?

If T= 5/9(K-32), and if T= 290, then K=

(a) 17938/9
(b) 322
(c) 490
(d) 554
(e) 2898/5

Thanks in advance!
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sunny.jain
 Post subject: Re: Is calculation the only way?
 Post Posted: Fri Sep 04, 2009 12:59 am 
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Students


Posts: 111
Well, you can choose to do half calculation:

T = 5*(k-32)/9

290*9/5 = K - 32

58*9 + 32 = K

just calculate the unit digit:
8*9 + 2 = 4, so D is the answer.
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anoo.anand
 Post subject: Re: Is calculation the only way?
 Post Posted: Sat Sep 19, 2009 2:34 pm 
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Students


Posts: 73
( 290* 9 / 5 ) + 32 = k

=> k = ( 290 * 10 /5 ) + 32

= ( 290 * 10 * 2 / (5*2) ) + 32

= double of 290 + 32

= approx 600 but in 550 range... ;) ...so D
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RonPurewal
 Post subject: Re: Is calculation the only way?
 Post Posted: Sat Sep 26, 2009 2:46 am 
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ManhattanGMAT Staff


Posts: 7146
mwilliams82 wrote:
The more I study the gmat the more obsessed I've become with finding out how to find answers w/o calculation. I know how to calculate such problems as the following but have realized calculation is often the number one culprit that derails my timing and causes careless errors. SO, can the following problem be solved by ball-parking or abstract logic?

If T= 5/9(K-32), and if T= 290, then K=

(a) 17938/9
(b) 322
(c) 490
(d) 554
(e) 2898/5

Thanks in advance!


this was a GMATPREP problem? really?

anyway, mwilliams, the best thing for you to do is check out grade-school arithmetic and pre-algebra textbooks from the library, and PRACTICE.

i am not kidding.
you can't expect to run the other way every time you see arithmetic on the test!

not to mention that practicing your arithmetic is WAY easier than trying to develop a whole new theory on how to circumvent doing arithmetic.
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