UPSC Prelims 2026·CSAT·other·quantitative aptitude

The weight of X, in kg, is denoted by X. The weights of A, B, C, D, P, Q, R and S are measured. Given : A + B + C + D = 17 A + C = 6 P + Q + S + D = 15 P + Q + R + B = 17 P = R and Q = S Which one of the following statements is correct?

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  1. AB and D together weigh less than the total weight of P and Q.
  2. BP and Q together weigh more than the total weight of A and C.Correct
  3. CP weighs more than Q.
  4. DQ weighs more than P.

Explanation

To determine the correct statement, we must systematically solve the given system of linear equations.

1. Understand the given equations: We are provided with the following relationships:

  1. A + B + C + D = 17
  2. A + C = 6
  3. P + Q + S + D = 15
  4. P + Q + R + B = 17
  5. P = R
  6. Q = S

2. Simplify the relationships: Substitute equation (2) into equation (1): (A + C) + B + D = 17 6 + B + D = 17 B + D = 11

Next, substitute the equivalencies from equations (5) and (6) into equations (3) and (4): From (3): P + Q + Q + D = 15 => P + 2Q + D = 15 From (4): P + Q + P + B = 17 => 2P + Q + B = 17

3. Find the combined weight of P and Q: Add these two new equations together: (P + 2Q + D) + (2P + Q + B) = 15 + 17 3P + 3Q + B + D = 32

Substitute the known sum (B + D = 11) into this equation: 3(P + Q) + 11 = 32 3(P + Q) = 21 P + Q = 7

4. Evaluate the options:

  • Why Option B is correct: We mathematically established that P + Q = 7. We are explicitly given A + C = 6. Therefore, P and Q together (7) weigh more than A and C together (6).
  • Why Option A is incorrect: It claims B + D Q or Q > P.

Takeaway: When solving algebraic reasoning questions in CSAT, group known sums together (like A+C and B+D) to systematically eliminate variables and isolate the target expressions.

other: The weight of X, in kg, is denoted by X. The weights of A, B, C, D, P, Q, R and S are measured. Given : A + B + C + D =

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