1. A train 100 meters long completely passes a man walking at 6 km/hr in the same direction in 5 seconds and a car travelling in the same direction in 6 seconds. At what speed was the car
travelling? (km/hr = kilometres/hour)
a. 18 km/hr
b. 48 km/hr
c. 24 km/hr
d. 30 km/hr
EXPLANATION
A train 100 meter long completely passes a man walking in the same direction at 6 km/h in 5 seconds. (x = train)
5 = 100*18 / (x-6)*5
=> 5 = 1800 / (x-6)*5
=> 5 = 1800 / 5x-30
=> 25x – 150 = 1800
=> 25x = 1950
=> x = 78
A car travelling in the same direction in 6 seconds. (y = car)
6 = 100*18 / (x-y)*5
=> 6 = 1800 / (78-y)*5
=> 6 = 1800 / 390-5y
=> 2340 – 30 y = 1800
=> -30y = 1800 – 2340
=> -30y = -540
=> y = 18
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