Cost composition from two price equations: If 2 apples + 3 oranges + 1 pear cost Rs. 62 and 5 apples + 6 oranges + 4 pears cost Rs. 120, then find the total cost of 3 apples + 3 oranges + 3 pears.

Difficulty: Medium

Correct Answer: Rs. 58

Explanation:


Introduction / Context:
This linear-combination question avoids solving for individual prices by cleverly combining the two given equations to get the desired sum directly. Such problems reward recognizing how to express the target bundle in terms of the provided bundles.


Given Data / Assumptions:

  • 2A + 3O + P = 62.
  • 5A + 6O + 4P = 120.
  • Target: 3A + 3O + 3P = 3(A + O + P).


Concept / Approach:
Multiply the first equation by 4 to align the pear coefficient with the second, then subtract to eliminate P. From the resulting relation, read off A + 2O and back-substitute into the first equation to compute A + O + P. Finally triple it to get the requested cost of 3A + 3O + 3P.


Step-by-Step Solution:

4*(2A + 3O + P) = 8A + 12O + 4P = 248.Subtract (5A + 6O + 4P = 120): (8A−5A) + (12O−6O) = 248 − 120 ⇒ 3A + 6O = 128.Hence A + 2O = 128/3.From 2A + 3O + P = 62, write as (A + 2O) + (A + O + P) = 62.Thus A + O + P = 62 − 128/3 = 58/3.Therefore 3(A + O + P) = 58.


Verification / Alternative check:

Plugging unknowns that satisfy both equations will always yield 58 for 3A + 3O + 3P due to linearity; no need to solve each price.


Why Other Options Are Wrong:

  • Rs. 39, Rs. 46, Rs. 24: These contradict the derived linear combination, hence do not satisfy both given equations simultaneously.


Common Pitfalls:

  • Mistakes when subtracting equations, especially with aligned coefficients.
  • Trying to fully solve for A, O, P (unnecessary extra work).


Final Answer:

Rs. 58

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