speed/time

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speed/time

by cans » Wed Jun 08, 2011 3:39 am
Is the number of seconds required to travel d1 feet at
r1 feet per second greater than the number of seconds
required to travel d2 feet at r2 feet per second?
(1) d1 is 30 greater than d2.
(2) r1 is 30 greater than r2.
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by galaxian » Wed Jun 08, 2011 4:00 am
IMO C
As the Qs comes down to finding if d1/r1 > d2/r2 which can be answered by both the given statements.

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by krishnasty » Wed Jun 08, 2011 4:06 am
cans wrote:Is the number of seconds required to travel d1 feet at
r1 feet per second greater than the number of seconds
required to travel d2 feet at r2 feet per second?
(1) d1 is 30 greater than d2.
(2) r1 is 30 greater than r2.
basically, question is asking , is d1/r1 > d2/r2 ??

1 ) it means is d1/r1 > (d1-30)/r2 ?
We have no idea wat is r1 or r2 and what is the relation, Hence, insufficient

2) it means is d1/r1 > d2 /(r1-30) ?
again, no idea wat is d1 and d2. hence, insufficient

Combining both,
is d1/r1 > (d1-30)/(r1-30) ?
now, if d1 is greater than r1, then ans is yes. If d1 < r1, then, ans is no.

Hence, insufficent

IMO E

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by GMATGuruNY » Wed Jun 08, 2011 5:24 am
cans wrote:Is the number of seconds required to travel d1 feet at
r1 feet per second greater than the number of seconds
required to travel d2 feet at r2 feet per second?
(1) d1 is 30 greater than d2.
(2) r1 is 30 greater than r2.
Is d1/r1 > d2/r2?

Look for combinations that satisfy both statements:
Let d2=1, d1=31, r2=1, r1=31.
Is 31/31>1/1? No.

Let d2=1, d1=31, r2=2, r1=32.
Is 31/32>1/2? Yes.

Since the combinations above satisfy both statements, and in the first case the answer is No and in the second case the answer is Yes, insufficient.

The correct answer is E.
Last edited by GMATGuruNY on Wed Jun 08, 2011 5:34 am, edited 1 time in total.
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by galaxian » Wed Jun 08, 2011 5:33 am
oops.. that was a really stupid mistake on my part :|

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by adityamba » Wed Jun 08, 2011 6:49 am
Is it E?

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by rveeraga » Thu Jun 09, 2011 10:46 am
In inequalities, distributing to minimum expression helps, especially in data sufficiency.

Combining both statements,
is 30+d2/30+r2 > d2/r2 ? (we know that the variables are positive)
=> is 30r2+d2r2 > 30d2+d2r2 ?
=> is r2 > d2 ?

none of the statements give relation between r2 and d2. So, insufficient. E.

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by cans » Fri Jun 10, 2011 8:24 am
OA E
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