[GMAT math practice question]
John traveled the entire 50 km trip. If he travelled the first 20 km of the trip at a constant rate 40 km per hour and the remaining trip at a constant rate 20 km per hour, what is his average speed, in km per hour?
A. 20 km/h
B. 23 km/h
C. 25 km/h
D. 26 km/h
E. 27 km/h
John traveled the entire 50 km trip. If he travelled the fir
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Average speed = total distance/total travel timeMax@Math Revolution wrote:[GMAT math practice question]
John traveled the entire 50 km trip. If he travelled the first 20 km of the trip at a constant rate 40 km per hour and the remaining trip at a constant rate 20 km per hour, what is his average speed, in km per hour?
A. 20 km/h
B. 23 km/h
C. 25 km/h
D. 26 km/h
E. 27 km/h
total distance = 50 km
total travel time = time spent driving at 40 kmh + time spent driving at 20 kmh
time = distance/speed
So, time spent driving at 40 kmh = 20/40 = 1/2 hour
And time spent driving at 20 kmh = 30/20 = 3/2 hours
So, TOTAL travel time = 1/2 + 3/2 = 4/2 = 2 hours
Average speed = 50/2 = 25 kmh
Answer: C
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Leg 1:Max@Math Revolution wrote:[GMAT math practice question]
John traveled the entire 50 km trip. If he travelled the first 20 km of the trip at a constant rate 40 km per hour and the remaining trip at a constant rate 20 km per hour, what is his average speed, in km per hour?
A. 20 km/h
B. 23 km/h
C. 25 km/h
D. 26 km/h
E. 27 km/h
T = D/S
T = 20/40 = 1/2
Leg 2:
T = D/S
T = 30/20 = 3/2
Total time = 1/2 + 3/2 = 2
Avg Speed = D/T = 50/2 = 25
- Max@Math Revolution
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=>
Ave Speed = ( Total Distance ) / ( Total Time )
The total distance = 50 km.
Total time is 20 / 40 + 30 / 20 = 0.5 + 1.5 = 2
The average speed is 50 / 2 = 25.
Therefore, the answer is C.
Answer : C
Ave Speed = ( Total Distance ) / ( Total Time )
The total distance = 50 km.
Total time is 20 / 40 + 30 / 20 = 0.5 + 1.5 = 2
The average speed is 50 / 2 = 25.
Therefore, the answer is C.
Answer : C
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We can use the equation: average = total distance/total timeMax@Math Revolution wrote:[GMAT math practice question]
John traveled the entire 50 km trip. If he travelled the first 20 km of the trip at a constant rate 40 km per hour and the remaining trip at a constant rate 20 km per hour, what is his average speed, in km per hour?
A. 20 km/h
B. 23 km/h
C. 25 km/h
D. 26 km/h
E. 27 km/h
50/(20/40+ 30/20)
50/(1/2 + 3/2)
50/(4/2) = 50/2 = 25
Answer: C
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