nkmungila wrote:

A bike running at 80 km/h initially is slowed down to 60 km/h as soon as the fuel indicator touches the half level mark. It keeps running at this speed till it runs out of fuel, thereby covering a total distance of 640 km in 10 hours. If the bike consumes 2 litres of fuel per hour, what is the capacity (in litres) of the fuel tank of the bike?

(A) 16

(B) 20

(C) 32

(D) 40

(E) 56

Answer C.

I think the key is:

Half of the fuel is used at 60 km per hour.

When the bike started traveling at 60 km per hour, it started with exactly half a tank of fuel, all of which was used up.

So the segment at 60 km/hr will yield the capacity of the tank.

Fuel consumption rate is given in hours. We need time, in hours, that the bike travels at 60 km/hr.

Total time is 10 hours

Total distance is 640 km

Time for 60 kmh, segment 2, = T

Time for 80 kmh, segment 1 = (10 - T)

Segment 1 (r*t) + Segment 2 (r*t) = Total Distance

80(10 - T) + 60T = 640

800 - 80T + 60T = 640

20T = 160

T = 8

So time taken at 60 km per hour is 8 hours.

Amount of fuel used:

8 hrs * \(\frac{2L}{hr}\) = 16 Liters

16 Liters is only half of the fuel capacity. Full fuel capacity therefore is

16L * 2 = 32 Liters

ANSWER C

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