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A man travels from A to B at a speed of 50 km/hr and returns to A by increasing his speed by 30%. What is his average speed during the whole journey?
1. 56(12/23)
2. 57(1/2)
3. 56(2/3)
4. 52(1/3)

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Correct Answer - Option 1 : 56(12/23)

Given:

A man travels from A to B at a speed of 50 km/hr

He returns back by increasing his speed by 30%

Formula used:

Average speed = total distance covered/total time taken

Distance = speed × time

Calculation:

Let the distance travelled from A to B be ‘D’

Time taken to travel from A to B = D/50

Return speed = 130/100 × 50 = 65 km/hr

Time taken to travel back from B to A = D/65

Total distance = D + D = 2D

Total time taken = D/50 + D/65 = (13D +10D)/650 = 23D/650

Average speed = 2D/23D × 650

⇒ 1300/23

⇒ \(56{12\over 23}\)

  Average speed during the whole journey is \(56{12\over 23}\).

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