SPM 2023 Add Maths Paper 2, Question 14Linear Programming
Solved on video in English and Bahasa Melayu · Form 5, Linear Programming · 5:02 video
The question
Julie produces two types of dolls, Mal and Tod. Table 3 shows: Mal — x units at RM16.80 per unit; Tod — y units at RM14.00 per unit. The dolls satisfy the following constraints: I: the total number of Mal and Tod dolls is less than p units; II: the number of Tod dolls is more than q units; III: the number of Tod dolls is not more than 2 times the number of Mal dolls.
(a) Constraints I and II are shown on the provided graph; the shaded region represents the points satisfying both. State the value of p and of q.
Constraint III: the number of Tod dolls is not more than 2 times the number of Mal dolls; p = 16, q = 4.
(b) Write an inequality for constraint III, other than x ≥ 0 and y ≥ 0. Hence, construct and label the region R which satisfies all the constraints.
Use the region R constructed in (b).
(c)(i) On a particular day, the ratio of the number of Tod dolls to the number of Mal dolls produced is 3 : 2. Determine the possible numbers of Mal dolls produced on that day.
Mal costs RM16.80 per unit and Tod costs RM14.00 per unit; region R is as in (b).
(c)(ii) Given that the total cost to produce the Mal dolls and Tod dolls is RMk, express k in terms of x and y. Hence, draw the objective function and find the maximum cost.
5:02Part (a)
Step 1
Constraint I: x + y < p. From the graph the boundary line x + y = p has intercepts at 16, so p = 16.
Why this step
Turn the inequality into its boundary line x + y = p. Where that line meets an axis, x or y is 0, so the intercept equals p.
1 more step, with the reason for it, in the full solution
Final answer
p = 16, q = 4
Where students lose marks
Watch out: read both values. p comes from x + y = 16, and q from the horizontal line y = 4.
Part (b)
2 more steps, each with the reason for it, in the full solution
Final answer
y ≤ 2x; region R constructed (see video)
Where students lose marks
Watch out: R lies below y = 2x, above y = 4 and below x + y = 16. Check each side.
Part (c)(i)
3 more steps, each with the reason for it, in the full solution
Final answer
Mal = 4 or 6
Where students lose marks
Watch out: keep only whole-number points on y = (3/2)x inside R, or you will miss or add invalid x values.
Part (c)(ii)
4 more steps, each with the reason for it, in the full solution
Final answer
k = 16.80x + 14.00y; maximum cost = RM238 at (10, 5)
Where students lose marks
Watch out: after k = 16.8x + 14y, draw the objective line and slide it to the last point of R, (10, 5).
Watch every step of this question solved on video (5:02), with the reason behind each step and a box that checks your own answer.
No card. Every past-year question on video, in English and BM.
More Linear Programming questions
- SPM 2020 Add Maths Paper 2, Question 14
- SPM 2021 Add Maths Paper 2, Question 15
- SPM 2022 Add Maths Paper 2, Question 13
- SPM 2024 Add Maths Paper 2, Question 13
- Kuala Lumpur Trial 2025 Add Maths Paper 2, Question 12
- Melaka Trial 2025 Add Maths Paper 2, Question 15
- MRSM Trial 2025 Add Maths Paper 2, Question 13
- Selangor Trial 2025 Add Maths Paper 2, Question 15
Questions are re-typeset by Eduly for study and commentary. Eduly is not affiliated with Lembaga Peperiksaan Malaysia or the Ministry of Education.