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A person goes from point A to B and comes back. His average speed for the whole journey is 30 km/hr. If his speed while going from A to B i…

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A person goes from point A to B and comes back. His average speed for the whole journey is 30 km/hr. If his speed while going from A to B is 24 km/hr, then what will be the speed of the person (in km/hr) while coming back from B to A?

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Discussion 1

CCommunity24 May 2019

We know that,

If ‘x’ km/hr is the speed from A to B and ‘y’ km/hr is the speed from B to A then,

Average speed = 2xy/(x + y)

⇒ 30 = (2 × 24 × y)/(24 + y)

⇒ 15(24 + y) = 24y

⇒ 9y = 24 × 15

⇒ y = 40 km/hr

∴ The speed of the person while coming back from B to A = 40 km/hr