When it is 12 Noon in Cairo (30° Eastern Longitude) the time in London will be :

Question

Accepted Answer

The correct answer is Option 2: 10 A.M.

Here's why:

*   **Understanding Time Zones and Longitude:** The Earth is divided into 360 degrees of longitude. Since the Earth rotates 360 degrees in 24 hours, each 15 degrees of longitude corresponds to a one-hour time difference.

*   **Calculating the Time Difference:** Cairo is located at 30° East longitude, while London is located at approximately 0° longitude (Greenwich Mean Time). The difference in longitude between Cairo and London is 30 degrees.

*   **Converting Longitude Difference to Time Difference:** Since each 15 degrees of longitude represents one hour, a 30-degree difference represents 30/15 = 2 hours.

*   **Determining the Time in London:** Cairo is east of London. Locations east of a given point experience time *ahead* of that point. Therefore, London will be 2 hours *behind* Cairo. If it is 12 Noon in Cairo, it will be 12 Noon - 2 hours = 10 A.M. in London.

**Why the other options are incorrect:**

*   **Option 1: 2 P.M.** This is incorrect because it suggests London is ahead of Cairo by 2 hours, which is the opposite of the actual situation. Cairo is east of London, so Cairo should be ahead.
*   **Option 3: 1 P.M.** This is incorrect because it suggests London is ahead of Cairo by 1 hour, which is not supported by the 30-degree longitude difference.
*   **Option 4: 11 A.M.** This is incorrect because it suggests London is only 1 hour behind Cairo. The 30-degree longitude difference dictates a 2-hour difference.