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%
The OA is the option D.
What is the equation that I should use here to solve this PS question? I need some help experts. I ask for your help.
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Bob wants to run a mile in the same time as his sister.
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EconomistGMATTutor
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Hello Vincen.
Let's take a look at your question.
First of all, let's convert the time to seconds.
Bob's time = 640 secs.
His sister's time = 576 secs.
Now, if we improve the time of Bob by 10% we can get that the new time is: 640 - 64 = 576 secs.
So, the correct answer is the option [spoiler]D=10%[/spoiler].
I hope this explanation may help you.
I'm available if you'd like a follow-up.
Regards.
Let's take a look at your question.
First of all, let's convert the time to seconds.
Bob's time = 640 secs.
His sister's time = 576 secs.
Now, if we improve the time of Bob by 10% we can get that the new time is: 640 - 64 = 576 secs.
So, the correct answer is the option [spoiler]D=10%[/spoiler].
I hope this explanation may help you.
I'm available if you'd like a follow-up.
Regards.
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Scott@TargetTestPrep
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Vincen 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%
The OA is the option D.
What is the equation that I should use here to solve this PS question? I need some help experts. I ask for your help.
We should notice that in this question, "improving the time" means decreasing the time; therefore, we are looking for a percent decrease.
Bob's time is 10 40/60 = 10 2/3 = 32/3 minutes
His sister's time is 9 36/60 = 9 6/10 = 9 3/5 = 48/5 minutes
If we let n = the percent less, we have:
(32/3) x (100 - n)/100 = 48/5
(100 - n)/100 = 48/5 x 3/32
(100 - n)/100 = 3/5 x 3/2
(100 - n)/100 = 9/10
100 - n = 90
n = 10%
Alternate Solution:
Bob's current time is 10 minutes 40 seconds = 640 seconds.
His sister's current time is 9 minutes 36 seconds = 576 seconds.
Bob must improve his time by 640 - 576 = 64 seconds, and that is an improvement of (64/640) * 100 = 10 percent.
Answer: D
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