2015 CSAT, all questions
UPSC Prelims 2015 · CSAT
Question 38: Basic Numeracy
In a parking area, the total number of wheels of all the cars (four-wheelers) and scooters/motorbikes (two-wheelers) is 100 more than twice the number of parked vehicles. The number of cars parked is
a35
b45
c50
d55
AnswerUPSC’s answer is (c).
Let cars be c and two-wheelers s. Wheels = 4c + 2s. The vehicles number c + s, and twice that is 2c + 2s. The condition says 4c + 2s = 2c + 2s + 100, so 2c = 100 and c = 50. The two-wheelers cancel out, so the number of cars is 50 whatever the number of scooters.
Why each option is right or wrong
- (a) Wrong: 35 cars gives 2c = 70, not 100.
- (b) Wrong: 45 cars gives 2c = 90, not 100.
- (c) Right: 2c = 100, so c = 50.
- (d) Wrong: 55 cars gives 2c = 110, not 100.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2015, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.