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AMITAGARWAL2
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Buses A and B start from a common bus stop X. Bus A begins Updated on: 21 Aug 2013, 02:51
Originally posted by AMITAGARWAL2 on 20 Aug 2013, 18:22.
Last edited by Bunuel on 21 Aug 2013, 02:51, edited 1 time in total.
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75% (hard)

Question Stats:

64% (03:04) correct 36% (03:20) wrong based on 289 sessions

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Buses A and B start from a common bus stop X. Bus A begins to travel in a straight line away from bus B at a constant rate of 30 miles per hour. One hour later, bus B begins to travel in a straight line in the exact opposite direction at a constant rate of 80 miles per hour. If both buses travel indefinitely, what is the positive difference, in minutes, between the amount of time it takes bus B to cover the exact distance that bus A has covered and the amount of time it takes bus B to cover twice the distance that bus A has covered?

A. 36
B. 72
C. 132
D. 144
E. 180
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D
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Bunuel
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Buses A and B start from a common bus stop X. Bus A begins 21 Aug 2013, 03:03
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AMITAGARWAL2
Buses A and B start from a common bus stop X. Bus A begins to travel in a straight line away from bus B at a constant rate of 30 miles per hour. One hour later, bus B begins to travel in a straight line in the exact opposite direction at a constant rate of 80 miles per hour. If both buses travel indefinitely, what is the positive difference, in minutes, between the amount of time it takes bus B to cover the exact distance that bus A has covered and the amount of time it takes bus B to cover twice the distance that bus A has covered?

A. 36
B. 72
C. 132
D. 144
E. 180
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The amount of time it takes bus B to cover the exact distance that bus A has covered:

The distance covered by bus B = 80t = the distance covered by bus A = 30(t+1) = --> 80t = 30(t+1) --> t=3/5 hours.

The amount of time it takes bus B to cover twice the distance that bus A has covered:

The distance covered by bus B = 80T = twice the distance covered by bus A = 2*30(T+1) --> 80T = 2*30(T+1) --> T=3 hours.

T - t = 3 - 3/5 = 12/5 hours = 144 minutes.

Answer: D.

Similar question to practice: alex-and-brenda-both-stand-at-point-x-alex-begins-to-walk-a-128752.html (good one)

Hope it helps.
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maaadhu
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Buses A and B start from a common bus stop X. Bus A begins 20 Aug 2013, 19:14
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AMITAGARWAL2
Buses A and B start from a common bus stop X. Bus A begins to travel in a straight line away from bus B at a constant rate of 30 miles per hour. One hour later, bus B begins to travel in a straight line in the exact opposite direction at a constant rate of 80 miles per hour. If both buses travel indefinitely, what is the positive difference, in minutes, between the amount of time it takes bus B to cover the exact distance that bus A has covered and the amount of time it takes bus B to cover twice the distance that bus A has covered?

a 36
b72
c132
d144
e 180
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1st part: - In 1hr, Bus A covers 30 miles.

Relative speed of bus A & Bus B is (80-30) = 50mph.

So time required for Bus B to cover the exact distance as A is

50*t = 30
t=3/5 = 36min

2nd part

80*t=2d - B has to cover twice the distance
30*(t+1) = d - A traveled 1hr more and has to travel only only d

so

d/30 - 2d/80 = 1

D=120
& T= 3hrs = 180 min

Question asks for +ve difference between part 1 and part 2 in minutes

= 180-36 = 144min
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Buses A and B start from a common bus stop X. Bus A begins 19 Oct 2015, 04:42
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30(t+1)=80t

t=3/5h=36min

80t/30(t+1)=2

t=3h=180min

180-36=144

D
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Buses A and B start from a common bus stop X. Bus A begins 05 Jun 2018, 10:29
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AMITAGARWAL2
Buses A and B start from a common bus stop X. Bus A begins to travel in a straight line away from bus B at a constant rate of 30 miles per hour. One hour later, bus B begins to travel in a straight line in the exact opposite direction at a constant rate of 80 miles per hour. If both buses travel indefinitely, what is the positive difference, in minutes, between the amount of time it takes bus B to cover the exact distance that bus A has covered and the amount of time it takes bus B to cover twice the distance that bus A has covered?

A. 36
B. 72
C. 132
D. 144
E. 180
Show more

We see that bus A travels 1 more hour than bus B. So if we let t = the time, in hours, bus B will cover the same distance as bus A, then we have:

80t = 30(t + 1)

80t = 30t + 30

50t = 30

t = 30/50 = 3/5 hour = 36 minutes

If we let T = the time, in hours, bus B will cover twice the distance as bus A, then we have:

80T = 2[30(T + 1)]

80T = 60T + 60

20T = 60

T = 60/20 = 3 hours = 180 minutes

So the difference is 180 - 36 = 144 minutes.

Answer: D
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Buses A and B start from a common bus stop X. Bus A begins 13 May 2025, 09:32
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