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
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