53ʳᵈ to 55ᵗʰ B.P.S.C. (Pre) 2011
The time at Cairo is 2 hours ahead of Greenwich. Hence, it is located at-
a30° W longitude
b30° E longitude✓ Correct
c28° E longitude
d28° W longitude
Explanation
Cairo (Cairo, Egypt) is located at 30° 3′ N, 31° 14′ E. Since Cairo’s time is two hours ahead of Greenwich (0° longitude), it lies near 30° East longitude. The Earth rotates 360° in 24 hours; hence, it takes 4 minutes for the earth to travel 1° of longitude. Therefore, time difference at 30° longitude = 30 × 4 = 120 minutes, i.e., two hours. Hence, option (b) is the correct answer. Join ## Page 7 ## Day & Night
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