What is the distance between two places on the surface of the earth which are located 8°N and 10°S on the same longitude?

Analyze the question: Two places lie on the same longitude (the same meridian), one at 8°N and the other at 10°S. We need the north-south distance between them.

Concept: Along a meridian, the distance between two latitudes depends on the difference in latitude. One degree of latitude is about 111 km (the Earth's circumference is about 40,000 km, and 40,000 ÷ 360 ≈ 111 km).

Because the places are on opposite sides of the equator, we add the latitudes.

Solution:

1. Difference in latitude = 8° + 10° = 18°
2. Distance = 18 × 111 km = 1,998 km

(If you use 40,075 km for the circumference, you get 18 × 111.3 ≈ 2,004 km. This is still closest to 1,998 km.)

Checking the options:

• A (1,011 km) would be about 9° of latitude, which is too small.
• C (10,101 km) and D (17,770 km) are far too large.
• B (1,998 km) matches our calculation exactly.

Answer: B. 1,998 km

Tip: When two places are on the same longitude, ignore the longitude. If the latitudes are on the same side of the equator, subtract them. If they are on opposite sides, add them. Then multiply by 111 km. Notice that 18 × 111 = 1,998 is exactly the figure in option B.