2019 CSAT, all questions

UPSC Prelims 2019 · CSAT

Question 20: Logical Reasoning and Mental Ability

In a conference, out of a total 100 participants, 70 are Indians. If 60 of the total participants are vegetarian, then which of the following statements is/are correct ?

  1. 1.At least 30 Indian participants are vegetarian.
  2. 2.At least 10 Indian participants are non-vegetarian.

Select the correct answer using the codes given below :

a1 only
b2 only
cBoth 1 and 2
dNeither 1 nor 2

AnswerUPSC’s answer is (c).

There are 30 non-Indians. The 60 vegetarians include at most 30 non-Indians, so at least 60 - 30 = 30 Indians are vegetarian: statement 1. There are 40 non-vegetarians in all, and at most 30 of them can be non-Indians, so at least 40 - 30 = 10 Indians are non-vegetarian: statement 2. Both hold whatever the actual split is.

  • 1. At most 30 vegetarians are non-Indian, so at least 30 Indians are vegetarian.
  • 2. There are 40 non-vegetarians and at most 30 non-Indians, leaving at least 10 Indians.

How you could have got this

  1. If you were sure statement 1 is correct, (b) and (d) go: each of them leaves 1 out.

    What you needed to know: At most 30 vegetarians are non-Indian, so at least 30 Indians are vegetarian.

  2. Then, if you were sure statement 2 is correct, (a) goes: it leaves 2 out.

    What you needed to know: There are 40 non-vegetarians and at most 30 non-Indians, leaving at least 10 Indians.

Only (c) is left. This one needs every statement.

Which options go is worked out from UPSC’s key and the options, not by a model.

Why each option is right or wrong
  • (a) Wrong: statement 2 also holds.
  • (b) Wrong: statement 1 also holds.
  • (c) Right: both hold even in the worst case.
  • (d) Wrong: both statements hold.

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

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Source: UPSC, Civil Services (Preliminary) Examination 2019, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.