A passenger train takes 2 hours less for a journey of 300 km if its speed is increased by 5 km / hr from its usual speed. Find the usual speed of the train.
Time = distance/speed
Given, passenger train takes 2 hours less for a journey of 300 km if its speed is increased by 5 km / hr from its usual speed.
Let the usual speed be ‘a’.
⇒ 300 ×(a + 5 –a) = 2(a2 + 5a)
⇒ a2 + 5a – 750 = 0
⇒ a2 + 30a – 25a – 750 = 0
⇒ a(a + 30) – 25(a + 30) = 0
⇒ (a + 30)(a – 25) = 0
⇒ a = 25 km/hr
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