2009 General Studies, all questions
UPSC Prelims 2009 · General Studies
Question 70: Logical Reasoning and Mental Ability
A person travels 12 km due North, then 15 km due East, after that 15 km due West and then 18 km due South. How far is he from the starting point ?
a6 km
b12 km
c33 km
d60 km
AnswerThe answer is (a).
Take north as positive. The person goes 12 km north, then 15 km east and 15 km west, which cancel out. He then goes 18 km south. Net displacement: 12 - 18 = -6, so he is 6 km south of the starting point. Distance from the start is 6 km.
Why each option is right or wrong
- (a) Right: net displacement is 6 km (south).
- (b) 12 km is just the first leg, ignoring the southward 18 km.
- (c) 33 km comes from adding legs instead of taking the net north-south movement.
- (d) 60 km is the total path length, not the distance from the start.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2009, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.