Question
A is cycling at an average speed of 24 km/hr such that
he can reach a certain point at 12 noon. If he cycles at 40 km/hr, then he will reach the destination at 10 a.m. At what speed he should cycle to reach the destination at 11 a.m.Solution
Let the distance to be travelled be ‘x’ km Time taken when speed is 24 km/hr = (x/24) hours Time taken when speed is 40 km/hr = (x/40) hours According to the question, (x/24) – (x/40) = 2 Or, 5x – 3x = 2 × 120 Or, 2x = 240 km Or, x = 120 km Time taken to travel 120 km with speed of 24 km/hr = 120/24 = 5 hours Therefore, he started at 12 – 5 = 7 a.m. Therefore, required speed to reach the destination at 11 a.m. or 4 hours = 120/4 = 30 km/hr
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