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GRE Prep Club Team Member
Joined: 20 Feb 2017
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How far in kilometers can Scott drive into the country if he
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23 Mar 2020, 00:10
23 Mar 2020, 00:10
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Question Stats:
76% (01:37) correct
23% (01:22) wrong based on 26 sessions
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How far in kilometers can Scott drive into the country if he drives out at 40 kilometers per hour (kph), returns over the same road at 30 kph, and spends 8 hours away from home, including a 1-hour stop for lunch?
(A) 105
(B) 120
(C) 145
(D) 180
(E) 210
(A) 105
(B) 120
(C) 145
(D) 180
(E) 210
Re: How far in kilometers can Scott drive into the country if he
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06 Oct 2020, 15:36
06 Oct 2020, 15:36
1
Let the distance travelled by scott to town equal "d" and time he spent driving to town equal "t".
since scott used the same routes, the distance he travelled to town equals the distance he travelled back home.
The following equations can therefore be related:
1) d=40t distance travelled to town
2) d=30(7-t) distance travelled back home
40t=30x7-30t
t=3hrs
therefore d=40x3=120km
Answer is B
since scott used the same routes, the distance he travelled to town equals the distance he travelled back home.
The following equations can therefore be related:
1) d=40t distance travelled to town
2) d=30(7-t) distance travelled back home
40t=30x7-30t
t=3hrs
therefore d=40x3=120km
Answer is B
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Re: How far in kilometers can Scott drive into the country if he
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03 Feb 2021, 00:50
03 Feb 2021, 00:50
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Another Method:
When half of the distance is being covered at a speed X and the other half at a speed of Y, then, the Average speed is given by 2XY/(X+Y)
For this question, X = 40 Kmph and Y = 30 Kmph
So, Average speed = 2 x 40 x 30 / (40+30) = 240/7 Kmph
Now, Total distance covered would be Speed (average) x Time. Since, there was a waiting period of an hour: Time must be 7 hours (8-1).
Total Distance = 240/7 x 7 = 240 km
DONT forget that this distance is for 2-way, divide this by 2 for 1-way i.e. 120 km
Hence, option B
When half of the distance is being covered at a speed X and the other half at a speed of Y, then, the Average speed is given by 2XY/(X+Y)
For this question, X = 40 Kmph and Y = 30 Kmph
So, Average speed = 2 x 40 x 30 / (40+30) = 240/7 Kmph
Now, Total distance covered would be Speed (average) x Time. Since, there was a waiting period of an hour: Time must be 7 hours (8-1).
Total Distance = 240/7 x 7 = 240 km
DONT forget that this distance is for 2-way, divide this by 2 for 1-way i.e. 120 km
Hence, option B
