ABC26GN1518 · Average

Subject: General Aptitude · Chapter: Average · Exam: · Marks: · Difficulty:

Distance between two stations A and B is 778 km. A train covers the journey from A to B at 84 km per hour and returns back to A with a uniform speed of 56 km per hour. Find the average speed of the train during the whole journey.

Answer

Answer (as printed):

Explanation

Required average speed $=\left(\frac{2 x y}{x+y}\right) \mathrm{km} / \mathrm{hr}=\frac{2 \times 84 \times 56}{(84+56)} \mathrm{km} / \mathrm{hr}$ $$=\left(\frac{2 \times 84 \times 56}{140}\right) \mathrm{km} / \mathrm{hr}=67.2 \mathrm{km} / \mathrm{hr} .$$

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