Dhiraj goes to his school from his house at a speed of 3.8 km/hr and returns at 2.6 km/hr. If he takes 5 hours going and coming, the distance between his house and school is:
7.72 km
Let the one-way distance between the house and the school be \(d\) km.
Time going \(=\frac{d}{3.8}\) hr and time returning \(=\frac{d}{2.6}\) hr; their sum is 5 hr.
So \(\frac{d}{3.8}+\frac{d}{2.6}=5\), giving \(d\left(\frac{1}{3.8}+\frac{1}{2.6}\right)=5\).
Combine the fractions: \(\frac{1}{3.8}+\frac{1}{2.6}=\frac{2.6+3.8}{3.8\times2.6}=\frac{6.4}{9.88}\).
Therefore \(d\times\frac{6.4}{9.88}=5\), so \(d=\frac{5\times9.88}{6.4}=\frac{49.4}{6.4}=7.71875\) km.
Hence, the distance between his house and school is about 7.72 km.
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Important Questions from Average Speed
A person covers a certain distance at the speed of 60 kmph and returns to the starting point at a speed of 40 kmph . Find the average speed (in km/hour) of the person for the whole journey.
A train runs at a speed of 28 kmph for 4 hours and 30 kmph for 5 hours and the remaining 40 kms in one hour. What is the average speed per hour?
Kapil travels for 4.5 hours at a speed of 50 km / h and 7.5 hours at a speed of 70 km / h. At the end of it, he finds that he covered only 6/7 of the total distance. At what average speed should he travel so that the remaining distance traveled in 5 hours?
An express train travelled at an average speed of 100 km/hr, stopping for 3 minutes after every 75 km. How long it take to reach its destination 600 km from the starting point?
A car has to cover 125 kms in 5 hours. What will be the average speed of the car if it has covered 90 kms in the first 3 hours?
