Question

A train takes 2 hours less for a journey of 600 km , if its speed is increased by 10 km/hr from its original speed . The original speed of the train is

• A. 65 km/hr
• B. 60 km/hr
• C. 55 km/hr
• D. 50 km/hr

Answer 1

The correct option is D 50 km/hr

Given,

Let $x$ be the original speed of train

Total distance $=600km$

Time taken $=\frac{600}{x}$

New spped of train $=x+10$

Time taken $=\frac{600}{x+10}$

According to given condition,

$\frac{600}{x}-\frac{600}{x+10}=2$

$600(x+10)-600x=2x(x+10)$

$6000=2x^2+20x$

$2x^2+20x-6000=0$

$(x-50)(x+60)=0$

$\therefore x=-60,50$

$\therefore 50km$ is the original speed of train