DSC1520: Quantitative Modelling I
May/June Examination 2026 — Revision Guide
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Mathematics for Economics and Business
Exam Revision Guide
DSC1520
Module Code:
Quantitative Modelling I
Module Name:
May/June 2023 - May/June 2025
Papers Covered:
May/June Examination 2026
Focus Year:
100 marks (2 Hours)
Total Marks:
Programmable calculator permitted
Calculator:
Questions sourced from UNISA DSC1520 past papers (2023–2024). Work through
each answer step by step. Focus on understanding, not memorisation.
Exam Revision Notes | DSC1520 | 2026
,DSC1520 | Exam Revision May/June Examination 2026
PART 1: DSC1520 — May/June 2024 Examination
100 Marks | 2 Hours | Programmable Calculator Permitted
Page 2 of 30
, DSC1520 | Exam Revision May/June Examination 2026
Question 1 [20 marks]
(a) [8 marks]
Question: The demand and cost functions for a commodity are given by:
P = 40 − 0.2Q and C(Q) = 1 000 + 15Q
where P is the price per unit and Q is the quantity produced and sold.
(i) Determine the profit function π(Q). [2]
(ii) Find the break-even quantity (or quantities). [3]
(iii) Find the quantity that maximises profit, and state the maximum profit. [3]
Answer: (i) Profit function:
Total Revenue = P × Q = (40 − 0.2Q) Q = 40Q − 0.2Q2
π(Q) = T R − T C = (40Q − 0.2Q2 ) − (1 000 + 15Q)
π(Q) = −0.2Q2 + 25Q − 1 000
(ii) Break-even quantity:
Set π(Q) = 0:
−0.2Q2 + 25Q − 1 000 = 0
Multiply through by −5:
Q2 − 125Q + 5 000 = 0
Using the quadratic formula:
p √
125 ± 1252 − 4(1)(5 000) 125 ± 15 625 − 20 000
Q= =
2 2
∆ = 15 625 − 20 000 = −4 375 < 0
Page 3 of 30