A train is to cover 370 km at a uniform speed. After running 100 km, the train could run at a speed of 5 km/h less than its normal speed due to some technical fault. The train got delayed by 36 minutes. What is the normal speed of the train, in km/h?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 50
Let the x be the normal speed of the train,
⇒ 270/(x - 5) - 270/x = 36/60
⇒ 270(1/(x - 5) - 1/x) = 3/5
⇒ (x - x + 5)/x(x - 5) = 1/450
⇒ x2 - 5x = 2250
⇒ x2 - 5x - 2250 = 0
⇒ x2 - 50x + 45x - 2250 = 0
⇒ x(x - 50) + 45(x - 50) = 0
⇒ x = 50, -45