Rahul and Mithun travel a distance of 30 km. The sum of their speeds is 70 km/h and the total time taken by both to travel the distance is 2 hours 6 minutes. The difference between their speeds is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e 30 km/h
Let the speed of Rahul ykm/h the speed of Mithun will be (70 - y)km/h.
Time is taken by Rahul to cover distance = 30/y
Time is taken by Mithun to cover distance = 30/(70 - y)
⇒ Total time taken = 30 / y + 30/(70 - y) = 2 (1/10)
⇒ y2 - 70y + 1000 = 0
By solving the given quadratic equation
⇒ (y - 50)(y - 20) = 0
⇒ The difference between speeds = 50 - 20 = 30km/h