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# Je? and Ali race each other at the Tentleytown Speedway.

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Retired Moderator
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Je? and Ali race each other at the Tentleytown Speedway. [#permalink]  08 Dec 2017, 20:56
Expert's post
00:00

Question Stats:

13% (00:47) correct 86% (01:34) wrong based on 22 sessions
Jeff and Ali race each other at the Tentleytown Speedway. Ali’s car travels at 300 feet per second, and Je?’s car travels at 250 feet per second. If one lap around the track is 3000 feet long, and each car travels at a constant rate, how many laps will it take Ali to overtake Jeff?

A. 1
B. 5
C. 6
D. 10
E. 60

Drill 4
Question: 2
Page: 531
[Reveal] Spoiler: OA

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Retired Moderator
Joined: 07 Jun 2014
Posts: 4803
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
Followers: 171

Kudos [?]: 2915 [0], given: 394

Re: Je? and Ali race each other at the Tentleytown Speedway. [#permalink]  29 Dec 2017, 15:39
Expert's post
Explanation

Use the Rate Pie.

Ali is traveling 50 feet per second faster than Jeff is traveling. Therefore, that is the rate at which she is effectively gaining ground on him. Put that in the
lower-right segment of the Rate Pie. We want to know how long it will take her to gain 3,000 feet on him.

Put 3,000 in the top section of the Rate Pie. Now you can see that dividing $$\frac{3000}{50}$$ will fill in the last segment of the Rate Pie, telling you how long it takes Ali to do so is 60 seconds. Be aware that choice (E) is an incorrect partial answer.

Now you need to find out how many feet Ali will travel in 60 seconds, by multiplying 60 second × 300 feet per second, which equals 18,000 feet. Divide 18,000 feet by the length of one lap, or 3,000 feet, and you’ll find that it will take Ali 6 laps to overtake Jeff.

Hence option C is correct!
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Re: Je? and Ali race each other at the Tentleytown Speedway. [#permalink]  29 Dec 2017, 22:37
sandy wrote:
Explanation

Use the Rate Pie.

Ali is traveling 50 feet per second faster than Jeff is traveling. Therefore, that is the rate at which she is effectively gaining ground on him. Put that in the
lower-right segment of the Rate Pie. We want to know how long it will take her to gain 3,000 feet on him.

Put 3,000 in the top section of the Rate Pie. Now you can see that dividing $$\frac{3000}{50}$$ will fill in the last segment of the Rate Pie, telling you how long it takes Ali to do so is 60 seconds. Be aware that choice (E) is an incorrect partial answer.

Now you need to find out how many feet Ali will travel in 60 seconds, by multiplying 60 second × 300 feet per second, which equals 18,000 feet. Divide 18,000 feet by the length of one lap, or 3,000 feet, and you’ll find that it will take Ali 6 laps to overtake Jeff.

Hence option B is correct!

Answer should be C anyway. since B is 5 laps
Retired Moderator
Joined: 07 Jun 2014
Posts: 4803
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
Followers: 171

Kudos [?]: 2915 [0], given: 394

Re: Je? and Ali race each other at the Tentleytown Speedway. [#permalink]  30 Dec 2017, 05:57
Expert's post
I think you are right the answer should be indeed C.
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Intern
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Re: Je? and Ali race each other at the Tentleytown Speedway. [#permalink]  04 Jul 2018, 11:13
sandy wrote:
Explanation

Use the Rate Pie.

Ali is traveling 50 feet per second faster than Jeff is traveling. Therefore, that is the rate at which she is effectively gaining ground on him. Put that in the
lower-right segment of the Rate Pie. We want to know how long it will take her to gain 3,000 feet on him.

Put 3,000 in the top section of the Rate Pie. Now you can see that dividing $$\frac{3000}{50}$$ will fill in the last segment of the Rate Pie, telling you how long it takes Ali to do so is 60 seconds. Be aware that choice (E) is an incorrect partial answer.

Now you need to find out how many feet Ali will travel in 60 seconds, by multiplying 60 second × 300 feet per second, which equals 18,000 feet. Divide 18,000 feet by the length of one lap, or 3,000 feet, and you’ll find that it will take Ali 6 laps to overtake Jeff.

Hence option C is correct!

what is the rate pie?
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Re: Je? and Ali race each other at the Tentleytown Speedway. [#permalink]  04 Jul 2018, 11:17
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Expert's post
Relative speed of Ali with respect to Jeff is 50 feet/second.
Since the track is 3000 ft long, it takes Ali around (3000/50 = 60) seconds to overtake Jeff.
In 60 seconds, Ali will travel 300*60 = 18000 feet.

18000 feet will translate to 6 LAPS since one lap is around 3000 ft long

Therefore, Ali takes 6 laps to overtake Jeff(Option C)
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Re: Je? and Ali race each other at the Tentleytown Speedway.   [#permalink] 04 Jul 2018, 11:17
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