Fractions

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Fractions

by gmattesttaker2 » Thu May 30, 2013 11:13 pm
Hello,

Can you please tell me if my approach is correct here:

If abc not equals 0, is (a/b)/c = a/(b/c) ?

1) a = 1
2) c = 1

OA: B

My approach:

(a/b)/c = a/(bc)

and

a/(b/c) = (ac)/b

Is, a/(bc) = (ac)/b ?

i.e. is c^2 = 1 ?

i.e. is c = +1 or c = -1?

1) Insufficient
2) Suff.



Thank for your help,
Sri
Source: — Data Sufficiency |

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by Brent@GMATPrepNow » Fri May 31, 2013 5:34 am
gmattesttaker2 wrote:Hello,

Can you please tell me if my approach is correct here:

If abc not equals 0, is (a/b)/c = a/(b/c) ?

1) a = 1
2) c = 1

OA: B

My approach:

(a/b)/c = a/(bc)

and

a/(b/c) = (ac)/b

Is, a/(bc) = (ac)/b ?

i.e. is c^2 = 1 ?

i.e. is c = +1 or c = -1?

1) Insufficient
2) Suff.



Thank for your help,
Sri
Hi Sri,

Your approach of rephrasing the target question to get "Does c = 1 or -1?" is perfect.
Once you spend some time doing that work up front, the task of checking the statements is very easy.

Great work.

Cheers,
Brent

Aside: If anyone is interested, we have a free video that covers the technique of rephrasing the target question: https://www.gmatprepnow.com/module/gmat- ... cy?id=1100
Brent Hanneson - Creator of GMATPrepNow.com
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by gmattesttaker2 » Fri May 31, 2013 12:32 pm
Brent@GMATPrepNow wrote:
gmattesttaker2 wrote:Hello,

Can you please tell me if my approach is correct here:

If abc not equals 0, is (a/b)/c = a/(b/c) ?

1) a = 1
2) c = 1

OA: B

My approach:

(a/b)/c = a/(bc)

and

a/(b/c) = (ac)/b

Is, a/(bc) = (ac)/b ?

i.e. is c^2 = 1 ?

i.e. is c = +1 or c = -1?

1) Insufficient
2) Suff.



Thank for your help,
Sri
Hi Sri,

Your approach of rephrasing the target question to get "Does c = 1 or -1?" is perfect.
Once you spend some time doing that work up front, the task of checking the statements is very easy.

Great work.

Cheers,
Brent

Aside: If anyone is interested, we have a free video that covers the technique of rephrasing the target question: https://www.gmatprepnow.com/module/gmat- ... cy?id=1100

Hello Brent,

Hope all is well. Thanks a lot for your prompt feedback and for your help.

Best Regards,
Sri