# If it is 12.00 Noon in India, on which meridian will it be 7.00 am of the same day?

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If it is 12.00 Noon in India, on which meridian will it be 7.00 am of the same day?
1. 7.5 degree E. longitude
2. 7.5 degree W. Longitude
3. 75 degree E. Longitude
4. 75 degree W. Longitude

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Correct Answer - Option 4 : 75 degree W. Longitude

The correct answer is 75 degrees W. Longitude.

Finding Direction:

$\implies$Current time in India = 12:00 p.m.

$\implies$Time at required meridian = 7:00 a.m.

$\implies$Difference in time = 5 hrs, and this time at meridian(7:00 a.m.) is 5 hrs behind. Hence it is west direction.

Note: When time on a meridian is lagging with respect to the time of others, then it lies to the west

Calculation of Longitude:

As we know the Earth takes 24 hrs. for one complete rotation, so

$\implies$24 hrs. = 360°

$\implies$1 hr = $\frac {360} {24}$= 15°, thus the Earth rotates 15 degrees in 1 hr.

$\implies$In 5 hrs = 5 × 15° = 75°.

Hence at 75° West longitude, the time will be 7:00 a.m.