Prasad moves 10 km towards the north from his starting point, then turns towards the east and travels 20 km. From there he turns towards the south and continues for another 10 km, and finally he moves 7 km towards the west. How far is he from the starting point now?

Introduction / Context:
This is a straightforward distance and displacement problem based on a rectangular path. Prasad moves north, then east, then south, and finally west. The question asks for his straight line distance from the starting point after the entire journey, which is essentially the magnitude of his net displacement vector.

Given Data / Assumptions:

• Prasad travels 10 km north.
• He then travels 20 km east.
• He then travels 10 km south.
• He finally travels 7 km west.
• All movements are in straight lines and at right angles.

Concept / Approach:
We represent the movements on a coordinate plane. Let the starting point be (0, 0). North adds to y, south subtracts from y, east adds to x, and west subtracts from x. After computing the final coordinates, we use the distance formula distance = sqrt(x^2 + y^2) to find how far Prasad is from the starting point. Observing that some vertical movements cancel makes the calculation easier.

Step-by-Step Solution:
Start at (0, 0). Move 10 km north to (0, 10). Move 20 km east to (20, 10). Move 10 km south to (20, 0). Move 7 km west to (13, 0). Final coordinates relative to start: (13, 0). Straight line distance from start = sqrt(13^2 + 0^2) = 13 km.

Verification / Alternative check:
The 10 km north and 10 km south movements cancel, leaving no net vertical displacement. Horizontally, he moves 20 km east and then 7 km west, giving a net of 13 km east. Since there is no vertical separation, his distance from the starting point is simply 13 km, directly towards the east.

Why Other Options Are Wrong:
Option A: 10 km likely comes from misreading only the first northward leg as the displacement.
Option C: 3 km is the difference between 10 and 7, not between 20 and 7, and does not reflect the overall path.
Option D: 17 km is not supported by the net horizontal and vertical movements.
Option E: None of these is incorrect because 13 Km appears explicitly and is correct.

Common Pitfalls:
Learners sometimes sum all distances to estimate displacement or use the wrong pair of movements when subtracting. Another mistake is forgetting that the north and south segments are equal and cancel. Breaking the path into horizontal and vertical components before computing displacement is a reliable method.

Final Answer:
Prasad is 13 Km away from his starting point.