A person covers a certain distance between his house and office on motorcycle. Having an average speed of 30 km/h, he is late by 10 min. Ho… — Answer & Discussion

A person covers a certain distance between his house and office on motorcycle. Having an average speed of 30 km/h, he is late by 10 min. However with a speed of 60 km/h, he reaches his office 5 min earlier. Find the distance between his house and office.

A15 km
B12 km
C7 km
D8 km

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Discussion 1

CCommunity06 May 2019

Let the distance be x km

∴ time taken to travel distance x km at an average speed of 30 km/hr = x/30 hr

Since the time taken is calculated by the formula - > t = distance/average speed

Also time taken when avg speed is 60 km/hr = x/60 hr

Now, time difference between them is 10 + 5 mins = 15 mins = 1/4 hr

∴ x/30 - x/60 = ¼

⇒ x = 15 km

∴ the distance between the house and office is 15 km