2016 CSAT, all questions
UPSC Prelims 2016 · CSAT
Question 58: Logical Reasoning and Mental Ability
A person walks 12 km due north, then 15 km due east, after that 19 km due west and then 15 km due south. How far is he from the starting point ?
a5 km
b9 km
c37 km
d61 km
AnswerUPSC’s answer is (a).
Net north-south: 12 km north then 15 km south leaves 3 km south. Net east-west: 15 km east then 19 km west leaves 4 km west. Distance from the start = sqrt(3^2 + 4^2) = 5 km (the 3-4-5 triple). Remember: add opposite moves as signed numbers, then use Pythagoras at the end.
Why each option is right or wrong
- (a) Right: 3 km south and 4 km west give 5 km.
- (b) 9 km does not follow from the net moves of 3 and 4.
- (c) 37 km does not follow from the net moves.
- (d) 61 km is the total distance walked, not the distance from the start.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2016, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.