On the Earth's surface, one degree of latitude corresponds to approximately how many kilometres of distance?

Introduction / Context:
This question is about basic mathematical geography. It asks how many kilometres on the Earth's surface correspond to a change of one degree in latitude. This value is important when estimating distances on maps and when understanding the scale of global movement. Being able to recall this approximate figure helps in many map-based and navigation-related questions.

Given Data / Assumptions:

• We are considering the Earth as approximately spherical.
• The question is specifically about latitude, not longitude.
• Options provided are 11 km, 211 km, 111 km and 311 km.
• We assume the standard average value taught in geography.

Concept / Approach:
Latitude lines are parallel and the distance between each degree of latitude is almost constant because we are moving north–south along meridians. The Earth's circumference along a great circle is about 40,000 km. There are 360 degrees in a circle, so the distance per degree is roughly 40,000 / 360, which is around 111 km. This approximate value is widely used in geography and navigation.

Step-by-Step Solution:
Step 1: Recall that the Earth's circumference is about 40,000 km. Step 2: Note that there are 360 degrees in a full circle around the Earth. Step 3: Compute the approximate distance per degree: 40,000 / 360 ≈ 111 km. Step 4: Compare this result with the options: 11 km, 211 km, 111 km and 311 km. Step 5: Identify 111 km as the closest and standard value and select it.

Verification / Alternative Check:
A quick check is to remember the rule of thumb used in navigation: approximately 60 nautical miles per degree of latitude. Since one nautical mile is about 1.852 km, 60 nautical miles correspond to about 111 km. This reinforces the result obtained by dividing the Earth's circumference by 360. Hence, both conceptual and numerical checks point to the same approximate distance of 111 km per degree of latitude.

Why Other Options Are Wrong:
Option a (11 km) is far too small for a degree and would give an Earth circumference of only about 4,000 km, which is incorrect. Option b (211 km) and option d (311 km) are too large, suggesting an Earth much bigger than known. Neither of those values is used in standard geography or navigation texts. They serve only as distractors and do not match well-known calculations.

Common Pitfalls:
Some students misremember the value and may drop a digit, choosing 11 km instead of 111 km. Others confuse degrees of latitude with degrees of longitude, where the distance per degree decreases towards the poles, but even then 11 km or 311 km would still be unrealistic. To avoid these mistakes, remember a simple association: “1 degree of latitude ≈ 111 km or 60 nautical miles.”

Final Answer:
One degree of latitude corresponds to an approximate distance of 111 kilometres on the Earth's surface.