CSAT Solved Papers/ 2021/Q70

2021 CSAT — Q70

Quant Statement validity 2.5 marks Hard

An amount of money was distributed among AA, BB and CC in the ratio p:q:rp:q:r.

Consider the following statements:

  1. AA gets the maximum share if pp is greater than (q+r)(q+r).

  2. CC gets the minimum share if rr is less than (p+q)(p+q).

Which of the above statements is/are correct?

  1. A Only 1 Answer
  2. B Only 2
  3. C Both 1 and 2
  4. D Neither 1 nor 2

Worked rationale

Shares are proportional to p,q,rp, q, r (all positive). The maximum/minimum share corresponds to the largest/smallest of p,q,rp, q, r.

Statement 1: if p>q+rp > q + r, then since q,r>0q, r > 0 we have p>qp > q and p>rp > r, so pp is the largest \Rightarrow AA gets the maximum. Correct (the condition is sufficient).

Statement 2: "r<p+qr < p + q" does not force rr to be the smallest. Counterexample: p=1,q=1,r=1.5p = 1, q = 1, r = 1.5. Here r=1.5<p+q=2r = 1.5 < p + q = 2, yet rr is the largest, so CC gets the maximum, not the minimum. Incorrect.

Answer: (a) Only 1.

Why the other options miss

  • B
    claimed more than the numbers allow: accepts the false Statement 2 and rejects the true Statement 1, likely by misreading ”p>q+rp > q+r.”
  • C
    missed a case: takes "r<p+qr < p + q" as ”rr is smallest” without testing a counterexample.
  • D
    solved the wrong question: denies that p>q+rp > q + r makes pp the largest, missing that q,r>0q, r > 0.

Specialist insight

A part is largest iff it exceeds each other part — and “exceeds the sum of the others” (p>q+rp > q+r) is a stronger condition that certainly does so, validating Statement 1. But “less than the sum of the others” (r<p+qr < p+q) is weak: nearly every component satisfies it, so it can’t pin rr as smallest — one counterexample (1,1,1.51,1,1.5) demolishes Statement 2. The trap is symmetry-bias: students assume the second condition mirrors the first. Test the boundary with a quick counterexample before trusting a “min” claim.

The trap, in one line

p>q+rpp>q+r \Rightarrow p largest (S1 true); but r<p+qr<p+q allows rr largest (e.g. 1,1,1.51,1,1.5), so S2 false \Rightarrow (a).

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