Kunal walks 10 km North, then 6 km South, and then 3 km East. How far from the start is he now, and in which direction relative to the starting point?
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A5 kilometers West
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B5 kilometers North-east
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C7 kilometers East
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D7 kilometers West
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ENone of these
Answer
Correct Answer: 5 kilometers North-east
Explanation
Introduction / Context:Position-tracking problems reduce to adding vectors on the North–South and East–West axes, then computing the resultant distance and bearing quadrant.
Given Data / Assumptions:
- North movement: +10 km; South movement: −6 km; net North = 4 km.
- East movement: +3 km; no West movement.
- Resultant from origin: (East 3 km, North 4 km).
Concept / Approach:Compute Pythagorean distance and determine the quadrant. The pair (3, 4) is the classic 3-4-5 right triangle.
Step-by-Step Solution:Net North = 10 − 6 = 4 km.Net East = 3 km.Distance = sqrt(3^2 + 4^2) = sqrt(9 + 16) = sqrt(25) = 5 km.Direction: East positive and North positive ⇒ North-East quadrant.
Verification / Alternative check:Draw a quick coordinate sketch: starting at (0,0), you end at (3,4). The straight line back to origin is 5 km, heading South-West; hence from origin to the point is North-East 5 km.
Why Other Options Are Wrong:
- 5 km West / 7 km East / 7 km West: wrong magnitude or axis.
- None of these: unnecessary, as 5 km North-East is exact.
Common Pitfalls:Subtracting incorrectly on the North–South axis or forgetting that bearing is from the start to the final point.
Final Answer:5 kilometers North-east