A migrating bird first flies 40 km towards the north from its initial position, then turns towards the east and flies 50 km, then turns again towards the north and flies another 110 km, and finally turns to its left and flies 50 km. Based on this complete flight path, where is the bird now with reference to its starting position in terms of direction and distance?

Introduction / Context:
This problem deals with a sequence of movements in different directions and asks for the final position relative to the starting point. It uses distances in kilometres and simple cardinal directions, which makes it a straightforward displacement question once the movements are broken into their horizontal and vertical components. These types of questions commonly appear under direction sense and basic analytical reasoning sections.

Given Data / Assumptions:

• The bird flies 40 km north from the starting point.
• It then turns east and flies 50 km.
• Next, it turns north and flies 110 km more.
• Finally, it turns to its left and flies 50 km.
• Turning left is defined relative to the current direction of motion.
• All flights are in straight lines and on a flat reference plane.

Concept / Approach:
We treat the starting point as the origin of a coordinate system. Movements towards the north and south affect the vertical coordinate, while movements towards the east and west affect the horizontal coordinate. Turning left from a given direction moves to the adjacent direction in the anticlockwise sense. After computing the final coordinates, we compare them with the starting point to obtain the net displacement and direction.

Step-by-Step Solution:
Step 1: Assume the starting point is (0, 0). After flying 40 km north, the bird reaches (0, 40). Step 2: It then turns east and flies 50 km, so the new position becomes (50, 40). Step 3: Now facing east, it turns north and flies another 110 km. Moving 110 km north increases the vertical coordinate to 40 + 110 = 150, giving the position (50, 150). Step 4: At this moment the bird is flying north. A left turn from north makes it face west. It then flies 50 km west, which reduces the horizontal coordinate from 50 to 0, placing it at (0, 150). Step 5: The starting point is (0, 0), and the final point is (0, 150). Therefore, the bird is 150 km directly north of its starting position.

Verification / Alternative check:
We can verify by looking at the net north south displacement. The bird has flown 40 km north and then 110 km north: a total of 150 km north. There is no southward motion at any stage, so the net vertical displacement is 150 km north. For the horizontal displacement, it flies 50 km east and subsequently 50 km west, which cancel each other out. Thus, only 150 km north remains as net displacement, confirming the result.

Why Other Options Are Wrong:
The options 150 km south and 70 km south reverse the correct direction, which contradicts the fact that there is no southward movement at all. The option 70 km north is inconsistent with the sum of the two legs towards the north, which clearly add up to 150 km. Therefore none of these alternatives match the correctly calculated displacement.

Common Pitfalls:
Many learners incorrectly add east and west distances without cancelling them, or mix up the left turn directions. Another error is to misread the distances and add only part of the northbound legs. Precisely listing each move and keeping track of net east west and net north south distances separately is crucial for accuracy.

Final Answer:
The migrating bird is now located 150 km north of its starting point.