The fuel consumed by a motorcycle during a journey while travelling at various speeds is indicated in the graph below (fuel consumption in litres per kilometre vs speed in km/h). The distances covered during four laps of the journey are listed in the table below:
Lap | Distance (kilometres) | Average Speed (kilometres per hour)
P | 40 | 15
Q | 75 | 50
R | 40 | 75
S | 20 | 10
From the given data, we can conclude that the fuel consumed per kilometre was least during the lap
A. P B. Q C. R D. S
GATE 2011 · General Aptitude · Line Graph · medium
Answer: Lap Q — at 50 km/h the motorcycle operates near its most fuel-efficient speed, giving the least fuel consumption per kilometre.
Read fuel consumption at each lap speed: S (10 km/h): graph is very steep on the left — high fuel/km (approx 0.09 L/km)
P (15 km/h): still on the steeply descending left part — high fuel/km (approx 0.07 L/km)
Q (50 km/h): near the bottom of the curve — lowest fuel/km (approx 0.04 L/km)
R (75 km/h): on the rising right side — moderate to high fuel/km (approx 0.06 L/km)
Identify the lap with lowest fuel per km: fuel_rate_Q < fuel_rate_R < fuel_rate_P < fuel_rate_S
Lap Q at 50 km/h is closest to the minimum of the U-shaped curve and hence has the lowest fuel consumption per kilometre.