2016 CSAT, all questions
UPSC Prelims 2016 · CSAT
Question 60: Basic Numeracy
Ram and Shyam work on a job together for four days and complete 60% of it. Ram takes leave then and Shyam works for eight more days to complete the job. How long would Ram take to complete the entire job alone ?
a6 days
b8 days
c10 days
d11 days
AnswerUPSC’s answer is (c).
Together they complete 60% in 4 days, which is 15% a day. Shyam alone does the remaining 40% in 8 days, which is 5% a day. So Ram does 15 - 5 = 10% a day and needs 100 / 10 = 10 days alone. Remember: work in percent per day and subtract the known rate.
Why each option is right or wrong
- (a) 6 days gives 16.7% a day, not 10%.
- (b) 8 days gives 12.5% a day, not 10%.
- (c) Right: 10% a day means 10 days.
- (d) 11 days gives about 9.1% a day, not 10%.
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.