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Train A is traveling at 40 miles per hour and Train B is traveling on

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Train A is traveling at 40 miles per hour and Train B is traveling on  [#permalink]

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16 Feb 2016, 00:02
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Question Stats:

84% (01:27) correct 16% (02:06) wrong based on 271 sessions

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Train A is traveling at 40 miles per hour and Train B is traveling on a parallel track in the same direction at 60 miles per hour. Currently, Train A is 15 miles ahead of Train B. How many minutes will it take Train B to catch up with Train A?

A. 45
B. 60
C. 75
D. 80
E. 90

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Posts: 3122
Re: Train A is traveling at 40 miles per hour and Train B is traveling on  [#permalink]

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09 Jun 2017, 09:33
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Bunuel wrote:
Train A is traveling at 40 miles per hour and Train B is traveling on a parallel track in the same direction at 60 miles per hour. Currently, Train A is 15 miles ahead of Train B. How many minutes will it take Train B to catch up with Train A?

A. 45
B. 60
C. 75
D. 80
E. 90

I call this a shrinking gap question.

Currently, Train A is 15 miles ahead of Train B.
So, the GAP = 15 miles

Train A is traveling at 40 miles per hour and Train B is traveling on a parallel track in the same direction at 60 miles per hour.
Speed difference = 60 mph - 40 mph = 20 miles per hour
So, the GAP shrinks at a rate of 20 miles per hour

How many minutes will it take Train B to catch up with Train A?
In others how long will it take the GAP to decrease from 15 miles to 0 miles.

Time = distance/rate
= (15 miles)/(20 miles per hour)
= 3/4 HOURS
= 45 minutes

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Joined: 26 Mar 2013
Posts: 1880
Re: Train A is traveling at 40 miles per hour and Train B is traveling on  [#permalink]

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17 Feb 2016, 02:41
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Bunuel wrote:
Train A is traveling at 40 miles per hour and Train B is traveling on a parallel track in the same direction at 60 miles per hour. Currently, Train A is 15 miles ahead of Train B. How many minutes will it take Train B to catch up with Train A?

A. 45
B. 60
C. 75
D. 80
E. 90

One approach

relative speed=60-40 =20 (same direction)

time = 15/20 *60 =45 min

other approach

0 hr 30 min 45min

A mile 15 35 45 (train A moves 40 miles in each hr so it moves 20 miles in 30 min and 10 mile in 15 min)

B mile 0 30 45 (train B moves 60 miles in each hr so it moves 30 miles in 30 min and 15 mile in 15 min)

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Re: Train A is traveling at 40 miles per hour and Train B is traveling on  [#permalink]

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13 Jun 2017, 11:14
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Bunuel wrote:
Train A is traveling at 40 miles per hour and Train B is traveling on a parallel track in the same direction at 60 miles per hour. Currently, Train A is 15 miles ahead of Train B. How many minutes will it take Train B to catch up with Train A?

A. 45
B. 60
C. 75
D. 80
E. 90

We are given that train Train A is traveling at 40 miles per hour and Train B is traveling on a parallel track in the same direction at 60 miles per hour. We need to determine how many minutes it will take Train B to catch Train A, since Train B must travel 15 more miles than Train A. Since both trains are traveling for the same amount of time, we can let each time = t hours.

Thus, Train A’s distance is 40t and Train B’s distance is 60t.

Since Train B travels 15 more miles than Train A:

40t + 15 = 60t

15 = 20t

15/20 = 3/4 = t

3/4 hour = 45 minutes

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Re: Train A is traveling at 40 miles per hour and Train B is traveling on  [#permalink]

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14 Jun 2017, 01:37
D=S*T
The question asks how long will it take to cover 15 miles with a relative speed of 20 mph (same direction so subtract speeds)

15=20*T, hence T=$$\frac{15}{20}$$ hours =$$\frac{15}{20}$$*60 mins = 45 mins
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Re: Train A is traveling at 40 miles per hour and Train B is traveling on  [#permalink]

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14 Jun 2017, 07:57
Bunuel wrote:
Train A is traveling at 40 miles per hour and Train B is traveling on a parallel track in the same direction at 60 miles per hour. Currently, Train A is 15 miles ahead of Train B. How many minutes will it take Train B to catch up with Train A?

A. 45
B. 60
C. 75
D. 80
E. 90

$$\frac{15}{(60-40)}*60$$ = 45 Minutes...

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Re: Train A is traveling at 40 miles per hour and Train B is traveling on  [#permalink]

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25 Jun 2017, 13:59

Without formulas and using some approximation

In 1 hr train A would have travelled 15+40=55 miles
In 1 hr train B would have travelled 60 miles. This means train B passes train A before hitting 60 minutes.
The only answer less than 60 is A
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Re: Train A is traveling at 40 miles per hour and Train B is traveling on  [#permalink]

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26 Jun 2017, 04:17
Train A is traveling at 40 miles per hour and Train B is traveling on a parallel track in the same direction at 60 miles per hour. Currently, Train A is 15 miles ahead of Train B. How many minutes will it take Train B to catch up with Train A?

Speed (Train A) = $$40 \frac{Miles}{Hour}$$

Speed (Train B) = $$60 \frac{Miles}{Hour}$$

Distance Between Train A and Train B = 15 Miles

As both Train A and Train B are moving in the same direction, we have to subtract the higher speed from the lower speed to get the relative speed

= $$60 \frac{Miles}{Hour}$$ - $$40 \frac{Miles}{Hour}$$ = $$20 \frac{Miles}{Hour}$$

So, lets calculate the time required for Train B to catch-up with Train A:

$$Time = \frac{Distance}{Speed}$$

$$= \frac{15}{20}$$

= 0.75 Hrs

As the time asked in the question is in minutes we will multiply it by 60

$$= 0.75 * 60$$

$$= 45 Min$$

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Re: Train A is traveling at 40 miles per hour and Train B is traveling on  [#permalink]

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15 Jul 2018, 18:21
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: Train A is traveling at 40 miles per hour and Train B is traveling on &nbs [#permalink] 15 Jul 2018, 18:21
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