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# Bob wants to run a mile in the same time

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Manager
Joined: 04 Apr 2010
Posts: 77
Schools: UCLA Anderson
Bob wants to run a mile in the same time  [#permalink]

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16 Jul 2015, 09:35
2
1
00:00

Difficulty:

25% (medium)

Question Stats:

78% (01:45) correct 22% (02:14) wrong based on 76 sessions

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Bob wants to run a mile in the same time as his sister. If Bob’s time for a mile is currently 10 minutes 40 seconds and his sister’s time is currently 9 minutes 36 seconds, by what percent does Bob need to improve his time in order run a mile in the same time as his sister?

(A) 3%
(B) 5%
(C) 8%
(D) 10%
(E) 12%

Source: Original question
Senior Manager
Joined: 28 Jun 2015
Posts: 279
Concentration: Finance
GPA: 3.5
Re: Bob wants to run a mile in the same time  [#permalink]

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16 Jul 2015, 09:44
1
Bob's time = 640 secs.
His sis' time = 576 secs.

Percent increase needed = (640-576/640) * 100 = 64/640 * 100 = 10%. Ans (D).
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Joined: 20 Mar 2014
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Concentration: Finance, Strategy
Schools: Kellogg '18 (M)
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Re: Bob wants to run a mile in the same time  [#permalink]

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16 Jul 2015, 10:02
1
TheGmatTutor wrote:
Bob wants to run a mile in the same time as his sister. If Bob’s time for a mile is currently 10 minutes 40 seconds and his sister’s time is currently 9 minutes 36 seconds, by what percent does Bob need to improve his time in order run a mile in the same time as his sister?

(A) 3%
(B) 5%
(C) 8%
(D) 10%
(E) 12%

Source: Original question

2 things to do in this question:

1. COnvert all minutes to seconds for ease of calculation.
2. Start with 10% for ease of calculations. Plugging in is better than doing the algebra for this question.

Looking at the "current" times for Bob and his sister respectively--->Tb = 640 seconds, Ts= 576, we see that 10% of 640 will be 64 and 640 -64 = 576 = Ts. Thus Bob neeeds to better his time by 10% to match up with his sister's time. Thus D is the correct answer.
Re: Bob wants to run a mile in the same time   [#permalink] 16 Jul 2015, 10:02
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