CSAT Solved Papers/ 2024/Q57

2024 CSAT — Q57

Quant Logical & quantitative reasoning 2.5 marks Easy

A person walks 100100 m Westward, then turns left and walks 100100 m. He then takes 225225^\circ turn clockwise. In which direction is he walking now?

  1. A South-West
  2. B South-East
  3. C North-West
  4. D North-East Answer

Worked rationale

This is a heading-only problem — the distances are decoys. Track the facing direction as a clockwise bearing (North =0=0^\circ, East =90=90^\circ, South =180=180^\circ, West =270=270^\circ).

  • He walks West, so his heading is 270270^\circ.
  • He turns left. Facing West, the left hand points South, so he is now facing South (180180^\circ).
  • He turns 225225^\circ clockwise: 180+225=40545(mod360)180^\circ + 225^\circ = 405^\circ \equiv 45^\circ \pmod{360^\circ}.

A bearing of 4545^\circ is North-East.

Answer: (d) North-East.

Visual solution

The same solve, worked by hand — read it, then trace it.

Hand-drawn worked solution for UPSC 2024 CSAT Q57 — Logical & quantitative reasoning
Tap the drawing to open it full size for the fine detail.

Why the other options miss

  • A
    solved the wrong question: treats the 225225^\circ turn as anticlockwise, sending the heading to 18022545315180^\circ - 225^\circ \equiv -45^\circ \equiv 315^\circ (North-West direction) or mis-signs it into the South-West quadrant.
  • B
    an arithmetic slip: adds only 135135^\circ (the supplement of 225225^\circ) to South, reaching 315315^\circ/135135^\circ and mislabelling it South-East.
  • C
    takes the turn from the wrong reference heading: turns left correctly to South but then takes the turn from West (270270^\circ) instead of South, giving 270+225=135270^\circ + 225^\circ = 135^\circ mis-read, or applies the 225225^\circ to the wrong reference heading.

Specialist insight

The only two steps that carry marks are: (i) a left turn while facing West lands you facing South, and (ii) bearing arithmetic mod 360360^\circ. Converting ”225225^\circ clockwise” into ”+225+225^\circ on the bearing” removes every chance of a sign error — 180+225=40545180 + 225 = 405 \equiv 45^\circ. The 100100 m legs never enter the answer; recognising that early saves the time a candidate would waste drawing a scaled path.

The trap, in one line

Carry the facing direction as a clockwise bearing: West \to left == South (180)(180^\circ), +225=40545=+225^\circ = 405^\circ \equiv 45^\circ = North-East (d)(d); the distances are decoys.

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