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:
Answer & explanation
Correct answer: option 1
Total time = 2 hours 6 minutes = \(\frac{21 }{10}\) hours
Let speed of Rahul = a km/h & Speed of Mithun = ( 70 - a ) km/h
Using formula :- Time = \(\frac{Distance }{Speed}\)
ATQ,
\(\frac{30 }{a}\) + \(\frac{30 }{70 - a }\) = \(\frac{21 }{10}\) hours
\(\frac{10 }{a}\) + \(\frac{10 }{70 - a }\) = \(\frac{7 }{10}\)
a² - 70a + 1000 = 0
On solving , a = is either 50 km/h or 20 km/h
SO , Difference b/w their speed = 50 - 20 = 30 km/h