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- Check units.
- Convert if needed.
- Apply S = D/T, D = S x T, or T = D/S.
Correct Answer: B
Correct Answer: B
Method / Topic: Time Speed Distance
The answer uses consistent units in the speed-distance-time relation.
Short Explanation
Detailed Explanation
Correct Answer: B
Method / Topic: Time Speed Distance
<table cellspacing="0" style="border-collapse:collapse; width:85px">
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<td style="border-bottom:none; border-left:none; border-right:none; border-top:none; height:20px; vertical-align:bottom; white-space:normal; width:85px">For equal distances, average speed = 2xy/(x+y). Here x=50 and y=75. Average speed = 2×50×75/(50+75) = 7500/125 = 60 km/h. Do not take the simple average of 50 and 75 because time taken is different.</td>
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</table>
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Learn + Solve: Shortcut, Trap & Fast Route Click to view shortcut, steps, and common mistake
Shortcut used, common trap, and the fastest solving route
- Check units.
- Convert if needed.
- Apply S = D/T, D = S x T, or T = D/S.
A car travels 150 km at a speed of 50 km/h and returns at 75 km/h. Find the average speed for the whole journey.
Explanation
Correct Answer: B
Method / Topic: Time Speed Distance
The answer uses consistent units in the speed-distance-time relation.
Short Explanation
Detailed Explanation
Correct Answer: B
Method / Topic: Time Speed Distance
<table cellspacing="0" style="border-collapse:collapse; width:85px">
<tbody>
<tr>
<td style="border-bottom:none; border-left:none; border-right:none; border-top:none; height:20px; vertical-align:bottom; white-space:normal; width:85px">For equal distances, average speed = 2xy/(x+y). Here x=50 and y=75. Average speed = 2×50×75/(50+75) = 7500/125 = 60 km/h. Do not take the simple average of 50 and 75 because time taken is different.</td>
</tr>
</tbody>
</table>
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