CBSE Class 10 Mathematics Basic 2024: question 33
Set in the CBSE Class 10 board exam of 2024, paper 430/5/1, section D, question 33, for 5 marks. Try it first; the hints and our step-by-step solution are below.
Q33 · 5 marks · Long answerCompetency-basedPair of Linear Equations in Two Variables
The ratio of monthly incomes of two persons is 9 : 7 and the ratio of their expenditures is 4 : 3. If each of them manages to save ₹ 2,000 per month, then find their monthly incomes.
Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 430/5/1.
Hints
Open one hint at a time and try again before the next.
Hint 1
Use two different variables for the income ratio and the expenditure ratio.
Hint 2
Income − expenditure = saving gives two linear equations; eliminate .
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 mark
Let the monthly incomes be ₹ and ₹, and the expenditures be ₹ and ₹.
- 1 mark
Saving = income − expenditure, so for the first person: ...(i)
- 1 mark
For the second person: ...(ii)
- 1 mark
(i)×3: ; (ii)×4: . Subtracting: (and then ).
- 1 mark
Monthly incomes: and .
Answer: ₹18,000 and ₹14,000
Where the marks are
- Takes incomes 9x, 7x and expenditures 4y, 3y (1 mark)
- Forms (1 mark)
- Forms (1 mark)
- Solves to get (1 mark)
- States incomes ₹18000 and ₹14000 (1 mark)
Revise the chapter
- Chapter: Pair of Linear Equations in Two Variables (notes, formulas, where marks are lost and every past question)
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