2016 CSAT, all questions

UPSC Prelims 2016 · CSAT

Question 76: Basic Numeracy

W can do 25% of a work in 30 days, X can do 1/4 of the work in 10 days, Y can do 40% of the work in 40 days and Z can do 1/3 of the work in 13 days. Who will complete the work first ?

aW
bX
cY
dZ

AnswerUPSC’s answer is (d).

Time to finish the whole work equals the time taken divided by the fraction done. W takes 30 / 0.25 = 120 days, X takes 10 / (1/4) = 40 days, Y takes 40 / 0.40 = 100 days, Z takes 13 / (1/3) = 39 days. Z has the smallest time, so Z finishes first. Remember: full time = time taken / fraction done.

Why each option is right or wrong
  • (a) W takes 120 days.
  • (b) X takes 40 days.
  • (c) Y takes 100 days.
  • (d) Right: Z takes 39 days, the least.

Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2016, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.