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A shopkeeper sells 50… (Class 12 Maths 2025, Q27b)

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MathsCBSE Class 12 · Board exam 2025, set 65/7/1 · 3 marks · Short answer

CBSE Class 12 Mathematics 2025: question 27(b)

Set in the CBSE Class 12 board exam of 2025, paper 65/7/1, section C, question 27(b), for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q27(b) · 3 marks · Short answerCompetency-basedMatrices

A shopkeeper sells 50 Chemistry, 60 Physics and 35 Maths books on day I and sells 40 Chemistry, 45 Physics and 50 Maths books on day II. If the selling price for each such subject book is ₹ 150 (Chemistry), ₹ 175 (Physics) and ₹ 180 (Maths), then find his total sale in two days, using matrix method. If cost price of all the books together is ₹ 35,000, what profit did he earn after the sale of two days ?

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 65/7/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Make a 2×3 matrix of books sold and a 3×1 matrix of prices.

Hint 2

Their product gives each day's sale. Add the two sales and subtract the cost price.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. Sales matrix (rows: Day I, Day II; columns: Chemistry, Physics, Maths) and price matrix .

    1 mark

  2. . So the sale is ₹ 24,300 on Day I and ₹ 22,875 on Day II.

    1 mark

  3. Total sale in two days = ₹ 24,300 + ₹ 22,875 = ₹ 47,175.

    ½ mark

  4. Profit = ₹ 47,175 − ₹ 35,000 = ₹ 12,175.

    ½ mark

Answer: Total sale ₹ 47,175; profit ₹ 12,175

Where the marks are

  • Forms the sales and price matrices correctly (1 mark)
  • Multiplies to get ₹24,300 and ₹22,875 (1 mark)
  • Total sale ₹47,175 (½ mark)
  • Profit ₹12,175 (½ mark)

Revise the chapter

  • Chapter: Matrices (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Matrices, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 65/7/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.