1995 General Studies, all questions

UPSC Prelims 1995 · General Studies

Question 141: Basic Numeracy

A student has 60% chance of passing in English and 54% chance of passing in both English and Mathematics. What is the percentage probability that he will fail in Mathematics?

a12
b36
c4
d10

AnswerThe answer is (d).

The chance of passing both English and Mathematics is 54%, and the chance of passing English is 60%. Treating the two results as independent, the chance of passing Mathematics is 54/60 = 0.9, or 90 per cent. So the chance of failing Mathematics is 100 - 90 = 10 per cent.

Why each option is right or wrong
  • (a) 12 does not follow from 54 / 60 = 0.9.
  • (b) 36 does not follow from 54 / 60 = 0.9.
  • (c) 4 does not follow from 54 / 60 = 0.9.
  • (d) Right: 10 per cent.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 1995, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.