If the time in Cairo (30° E Longitude) on Sunday is 12 Noon and in Newyork the time is 5 A. M. The longitude of Newyork is:

Question

Accepted Answer

The correct answer is Option 2: 75° W. Here's why:

**Explanation of why Option 2 (75° W) is correct:**

The Earth rotates 360 degrees in 24 hours, which means it rotates 15 degrees per hour (360/24 = 15). The time difference between Cairo (30° E) and New York is 7 hours (12 Noon in Cairo and 5 A.M. in New York).

Since New York is earlier than Cairo, it must be located west of Cairo. The 7-hour time difference translates to a longitudinal difference of 105 degrees (7 hours * 15 degrees/hour = 105 degrees).

Cairo is at 30° E. To find the longitude of New York, we subtract the longitudinal difference from Cairo's longitude because New York is west of Cairo: 30° E - 105° = -75°. Since longitude west is represented with a "W," the longitude of New York is 75° W.

**Explanation of why other options are incorrect:**

*   **Option 1: 20° W:** A longitude of 20° W would mean a much smaller time difference with Cairo. The longitudinal difference would only be 50 degrees (30° E + 20° W = 50°), resulting in a time difference of approximately 3 hours and 20 minutes (50 degrees / 15 degrees/hour = 3.33 hours). This doesn't match the given 7-hour time difference.

*   **Option 3: 60° W:** A longitude of 60° W would mean a longitudinal difference of 90 degrees (30° E + 60° W = 90°), resulting in a time difference of 6 hours (90 degrees / 15 degrees/hour = 6 hours). This is close, but not the exact 7-hour difference given in the problem.

*   **Option 4: 105° E:** A longitude of 105° E would place New York *east* of Cairo, meaning the time in New York would be *later* than in Cairo. This contradicts the given information that it is 5 A.M. in New York when it is 12 Noon in Cairo. Also, the longitudinal difference would be 75 degrees (105° E - 30° E = 75°), resulting in a time difference of 5 hours (75 degrees / 15 degrees/hour = 5 hours), which is not the 7-hour difference.