A train takes 
hours less for a journey of 300 km, if its speed is increased by 20 km/h from its usual speed. How much time will it take to cover a distance of 192 km at its usual speed?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e 4.8 hours
| Understanding | Application |
| We will use the concepts of time, speed, and distance, in addition to the concept of quadratic equations. |
Let the original speed of the train be 'v'. The difference in time will be ⇒ 5/2 = 300(1/v - 1/v + 20) ⇒ v2 + 20v - 2400 = 0 ⇒ (v - 40)(v + 60) ⇒ v = 40kmph The train will cover the distance of 192km in = 192/40 = 4.8 hours |