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NCERT Class 12 · Ch 3 Miscellaneous Exercise · Q7

NCERT Class 12 Maths · Chapter 3 Matrices · Miscellaneous Exercise Question 7

A manufacturer sells x,y,z in two markets, with annual quantity matrix \(\left[\begin{matrix}10000 & 2000 & 18000\\6000 & 20000 & 8000\end{matrix}\right]\) (rows: markets I,II; columns: x,y,z). (a) With unit prices ₹2.50,₹1.50,₹1, find revenue per market. (b) With costs ₹2,₹1,₹0.50, find gross profit.

💡 Concept Hints

  1. Check the matrix orders and the meaning of the requested operation before calculating.
  2. Keep row and column indices in order. Compare corresponding entries only after the matrix expressions have compatible dimensions.

✅ Step-by-Step Solution

Final Answer: Revenue: ₹46000,₹53000. Profit: ₹15000,₹17000; total ₹32000.
  1. Represent prices by \(\left[\begin{matrix}\frac{5}{2}\\\frac{3}{2}\\1\end{matrix}\right]\) and costs by \(\left[\begin{matrix}2\\1\\\frac{1}{2}\end{matrix}\right]\).
  2. Revenue vector = quantity matrix × price vector = \(\left[\begin{matrix}46000\\53000\end{matrix}\right]\).
  3. Unit profit vector is \(\left[\begin{matrix}\frac{1}{2}\\\frac{1}{2}\\\frac{1}{2}\end{matrix}\right]\). Multiplying by quantities gives \(\left[\begin{matrix}15000\\17000\end{matrix}\right]\).
  4. Hence gross profits are ₹15000 and ₹17000, totalling ₹32000.

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