The time taken by a person to cover 150 km was 2.5 hrs more than the time taken in the return journey. If he returned at a speed of 10 km / hr more than the speed of going, what was the speed per hour in each direction?
Time = distance/speed
Let the speed of person on onward journey be ‘a’ km/hr
Speed at which he returned = a – 10 km/hr
Given, time taken by a person to cover 150 km was 2.5 hrs more than the time taken in the return journey.
⇒ 150(a – a + 10) = 2.5a(a – 10)
⇒ 1500 = 2.5a2 – 25a
⇒ a2 – 10a – 600 = 0
⇒ a2 – 30a + 20a – 600 = 0
⇒ a(a – 30) + 20(a – 30) = 0
⇒ (a + 20)(a – 30) = 0
⇒ a = 30 km/hr
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