DSE Mathematics · Core

Past paper questions

Sample · Practise · Paper 1 & Paper 2 · 2012–2024

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2020 · Paper 1 Q1 Laws of integral indices
Simplify (mn2)5m4\frac{(mn^{-2})^{5}}{m^{-4}} and express your answer with positive indices.
2020 · Paper 1 Q2 Polynomials
Factorize
(a) α2+α6\alpha^{2}+\alpha-6 (3 marks)
(b) α4+α36α2\alpha^{4}+\alpha^{3}-6\alpha^{2} (3 marks)
2020 · Paper 1 Q3 Approximate values and numerical estimation
(a) Round up 534.7698534.7698 to the nearest hundred.
(b) Round down 534.7698534.7698 to 2 decimal places.
(c) Round off 534.7698534.7698 to 2 significant figures. (3 marks)
2020 · Paper 1 Q4 Rates, ratios and proportions
Let aa, bb and cc be non-zero numbers such that ab=67\frac{a}{b}=\frac{6}{7} and 3a=4c3a=4c. Find b+2ca+2b\frac{b+2c}{a+2b}. (3 marks)
2020 · Paper 1 Q5 Using percentages
In a recruitment exercise, the number of male applicants is 28%28\% more than the number of female applicants. The difference of the number of male applicants and the number of female applicants is 9191. Find the number of male applicants in the recruitment exercise. (4 marks)
2020 · Paper 1 Q6 Linear inequalities in one unknown
Consider the compound inequality
(a) Solve ()(*). 3x>7x2or5+x>43 - x > \frac{7 - x}{2} \quad \text{or} \quad 5 + x > 4
(b) Write down the greatest negative integer satisfying ()(*). (4 marks)
2020 · Paper 1 Q7 Quadratic equations in one unknown
(a) Let p(x)=4x2+12x+cp(x)=4x^{2}+12x+c, where cc is a constant. The equation p(x)=0p(x)=0 has equal roots. Find (a) cc,
(b) (b) the xx-intercept(s) of the graph of y=p(x)169y = p(x) - 169. (5 marks)
2020 · Paper 1 Q8 Angles and parallel lines
In Figure 1, BB and DD are points lying on ACAC and AEAE respectively. BEBE and CDCD intersect at the point FF. It is given that AB=BEAB = BE, BDCEBD \parallel CE, CAE=30\angle CAE = 30^\circ and ADB=42\angle ADB = 42^\circ.
Figure
(a) Find BEC \angle BEC .
(b) Let BDC=θ \angle BDC = \theta . Express CFE \angle CFE in terms of θ \theta

(5 marks)
2020 · Paper 1 Q9 Measures of dispersion
(a) Write down the mean, the median and the standard deviation of the above distribution.
(b) A new student now joins the class. The number of subjects taken by the new student is 55. Find the change in the median of the distribution due to the joining of this student. (5 marks)
2020 · Paper 1 Q10 Variations
(a) Find the price of a brand X souvenir of height 4 cm 4\text{ cm }.
(b) Someone claims that the price of a brand X souvenir of height 5 cm 5\text{ cm } is higher than the total price of two brand X souvenirs of height 4 cm 4\text{ cm }. Is the claim correct? Explain your answer. (2 marks)
2020 · Paper 1 Q11 Presentation of data
The stem-and-leaf diagram below shows the distribution of the weights (in grams) of the letters in a bag.
(a) Find ww.
(b) If a letter is randomly chosen from the bag, find the probability that the weight of the chosen letter is not less than the mode of the distribution. (2 marks)
2020 · Paper 1 Q12 Mensuration
(a) the volume of the middle part of the circular cone; (3 marks)
(b) the curved surface area of the middle part of the circular cone. (3 marks)
2020 · Paper 1 Q13 More about polynomials
The cubic polynomial f(x)f(x) is divisible by x1x-1. When f(x)f(x) is divided by x21x^{2}-1, the remainder is kx+8kx+8, where kk is a constant.
(a) Find kk. (3 marks)
(b) It is given that x+3x+3 is a factor of f(x)f(x). When f(x)f(x) is divided by xx, the remainder is 2424. Someone claims that all the roots of the equation f(x)=0f(x)=0 are integers. Is the claim correct? Explain your answer. (5 marks)
2020 · Paper 1 Q14 Equations of circles
The coordinates of the points A and B are (10,0)(-10,0) and (30,0)(30,0) respectively. The circle C passes through A and B. Denote the centre of C by G. It is given that the y-coordinate of G is -15.
(a) Find the equation of C. (3 marks)
(b) The straight line LL passes through BB and GG. Another straight line \ell is parallel to LL. Let PP be a moving point in the rectangular coordinate plane such that the perpendicular distance from PP to LL is equal to the perpendicular distance from PP to \ell. Denote the locus of PP by Γ\Gamma. It is given that Γ\Gamma passes through AA.
(i) Describe the geometric relationship between Γ\Gamma and LL.
(ii) Find the equation of II.
(iii) Suppose that Γ\Gamma cuts CC at another point HH. Someone claims that GAH<70\angle GAH < 70^{\circ}. Do you agree? Explain your answer. (6 marks)
2020 · Paper 1 Q15 Probability
In a box, there are 3 blue plates, 7 green plates and 9 purple plates. If 4 plates are randomly selected from the box at the same time, find
(a) the probability that 4 plates of the same colour are selected; (3 marks)
(b) the probability that at least 22 plates of different colours are selected. (2 marks)
2020 · Paper 1 Q16 Arithmetic and geometric sequences and their summations
The 3rd term and the 6th term of a geometric sequence are 144 and 486 respectively.
(a) Find the 1st1^{st} term of the sequence. (2 marks)
(b) Find the least value of nn such that the sum of the first nn terms of the sequence is greater than 8×10188 \times 10^{18}. (3 marks)
2020 · Paper 1 Q17 More about graphs of functions
Let g(x)=x22kx+2k2+4g(x) = x^{2} - 2kx + 2k^{2} + 4, where kk is a real constant.
(a) Using the method of completing the square, express, in terms of kk, the coordinates of the vertex of the graph of y=g(x)y = g(x). (2 marks)
(b) On the same rectangular coordinate system, let DD and EE be the vertex of the graph of y=g(x+2)y = g(x + 2) and the vertex of the graph of y=g(x2)y = -g(x - 2) respectively. Is there a point FF on this rectangular coordinate system such that the coordinates of the circumcentre of ΔDEF\Delta DEF are (0,3)(0, 3)? Explain your answer. (4 marks)
2020 · Paper 1 Q18 Similar triangles
Figure
(a) Prove that ΔUTVΔWTU\Delta UTV \sim \Delta WTU (2 marks)
(b) It is given that VWVW is a diameter of CC. Suppose that TU=780 cmTU = 780\text{ cm} and TV=325 cmTV = 325\text{ cm}
(i) Express the circumference of CC in terms of π\pi
(ii) Someone claims that the perimeter of ΔUVW\Delta UVW exceeds 35 m35\text{ m}. Do you agree? Explain your answer.
2020 · Paper 1 Q19 Mensuration
PQRS is a quadrilateral paper card, where PQ=60PQ = 60 cm, PS = 40 cm 40\text{ cm }, PQR=30\angle PQR = 30^\circ, PRQ=55\angle PRQ = 55^\circ and QPS=120\angle QPS = 120^\circ. The paper card is held with QR lying on the horizontal ground as shown in Figure 3.
Figure
(a) Find the length of RS.
(b) Find the area of the paper card. (2 marks)
(c) It is given that the angle between the paper card and the horizontal ground is 3232^{\circ}.
(i) Find the shortest distance from P to the horizontal ground.
(ii) A student claims that the angle between RS and the horizontal ground is at most 2020^{\circ}. Is the claim correct? Explain your answer. (7 marks)
2020 · Paper 1 Q Basic computation
2020 · Paper 2 Q1 Laws of integral indices
6x(3x5)2= \frac{6x}{(3x^{-5})^{-2}} =
A 54x8 54x^{8}
B 2x83 \frac{2x^{8}}{3}
C 54x9 \frac{54}{x^{9}}
D 23x9 \frac{2}{3x^{9}}
2020 · Paper 2 Q2 Formulae
a(a+b)=2(ba) a(a+b)=2(b-a) , then b=b=
A a2+a2+a \frac{a^{2}+a}{2+a}
B a22a2+a \frac{a^{2}-2a}{2+a}
C a2+2a2a \frac{a^{2}+2a}{2-a}
D a2a2a \frac{a^{2}-a}{2-a}
2020 · Paper 2 Q3 Algebraic expressions
54k+324k3= \frac{5}{4k+3}-\frac{2}{4k-3}=
A 12k2116k29 \frac{12k-21}{16k^2-9}
B 12k+916k29 \frac{12k+9}{16k^2-9}
C 14k2116k29 \frac{14k-21}{16k^2-9}
D 14k+916k29 \frac{14k+9}{16k^2-9}
2020 · Paper 2 Q4 Algebraic expressions
(3a+2b)(4a5b)a(6a+4b)=(3a+2b)(4a-5b)-a(6a+4b)=
A (3a+2b)(2a5b)(3a+2b)(2a-5b)
B (3a+2b)(6a5b)(3a+2b)(6a-5b)
C (3a2b)(2a+5b)(3a-2b)(2a+5b)
D (3a2b)(6a+5b)(3a-2b)(6a+5b)
2020 · Paper 2 Q5 More about polynomials
Let f(x)=3x2x2f(x)=3x^{2}-x-2. If β\beta is a constant, then f(1+β)f(1β)=f(1+\beta)-f(1-\beta)=
A 2β2\beta
B 10β10\beta
C 6β226\beta^{2}-2
D 6β22β6\beta^{2}-2\beta
2020 · Paper 2 Q6 More about polynomials
Let g(x)=ax3+4ax224g(x)=ax^{3}+4ax^{2}-24, where aa is a constant. If x+2x+2 is a factor of g(x)g(x), then g(2)=g(2)=
A
B 0.
C 48.
2020 · Paper 2 Q7 Identities
If hh and kk are constants such that (x+h)(x+6)(x+4)2+k(x+h)(x+6) \equiv (x+4)^{2}+k, then k=k =
A -28.
B -16.
C -4.
D 2.
2020 · Paper 2 Q8 Equations of straight lines
In the figure, the equations of the straight lines L1L_{1} and L2L_{2} are x+ay+b=0x + ay + b = 0 and bx+y+c=0bx + y + c = 0 respectively. Which of the following are true?
Figure
A I and II only
B I and III only
C II and III only
D I, II and III
2020 · Paper 2 Q9 Using percentages
The cost of a toy is x%x\% lower than its selling price. After selling the toy, the percentage profit is 25%25\%. Find xx.
A 2020
B 2525
C 7575
D 8080
2020 · Paper 2 Q10 Rates, ratios and proportions
The actual area of a golf course is 0.75 km20.75\text{ km}^{2}. If the area of the course on a map is 0.75 km20.75\text{ km}^{2} on a map is
A 1:2501:250.
B 1:50001:5000.
C 1:625001:62500.
D 1:250000001:25000000.
2020 · Paper 2 Q11 Variations
It is given that ww varies as the cube of uu and the square root of vv. When u=2u=2 and v=4v=4, w=8w=8. When u=4u=4 and v=9v=9, w=w=
A 9696.
B 324324.
C 384384.
D 729729.
2020 · Paper 2 Q12 Arithmetic and geometric sequences and their summations
In the figure, the 1st pattern consists of 3 dots. For any positive integer nn, the (n+1)(n+1)th pattern is formed by adding (2n+1)(2n+1) dots to the nnth pattern. Find the number of dots in the 7th pattern.

\bullet \bullet \bullet \quad \Longrightarrow \bullet \quad \bullet \quad \rightarrow \bullet \quad \bullet \quad \rightarrow \bullet \quad \bullet \quad \rightarrow \bullet \quad \bullet \quad \rightarrow \bullet \quad \bullet \quad \rightarrow \bullet \quad \bullet \quad \rightarrow
A 1515
B 2727
C 3838
D 5151
2020 · Paper 2 Q13 Linear inequalities in one unknown
The solution of 54x<95-4x<9 and 2x37>1\frac{2x-3}{7}>1 is
A x<1x<-1
B x>1x>-1
C x<5x<5
D x>5x>5
2020 · Paper 2 Q14 Errors in measurement
In the figure, PQRSTP_{QRST} is a pentagon, where all the measurements are correct to the nearest cm. Let Acm2A\, cm^2 be the actual area of the pentagon. Find the range of values of AA.
Figure
A 27.83A<31.8327.83 \leq A < 31.83
B 44.75A<60.7544.75 \leq A < 60.75
C 46.75A<63.2546.75 \leq A < 63.25
D 48.25A<64.7548.25 \leq A < 64.75
2020 · Paper 2 Q15 Arc lengths and areas of sectors
The angle of a sector is decreased by 60%60\% but its radius is increased by k%k\%. If the arc length of the sector remains unchanged, find the value of kk.
A 4040
B 6060
C 6767
D 150150
2020 · Paper 2 Q16 Mensuration
If the volume of a right circular cylinder of base radius 5acm5a \, cm and height 7bcm7b \, cm is 525cm3525 \, cm^{3}, then the volume of a right circular cone of base radius 7acm7a \, cm and height 5bcm5b \, cm is
A 175cm3175 \, cm^{3}
B 245cm3245 \, cm^{3}
C 490cm3490 \, cm^{3}
D 735cm3735 \, cm^{3}
2020 · Paper 2 Q17 Similar triangles
In the figure, P and Q are points lying on OR while U and T are points lying on OS such that OP=PQ=QROP = PQ = QR and PUQTRSPU \parallel QT \parallel RS. The ratio of the area of the trapezium QRSTQRST is
Figure
2020 · Paper 2 Q18 Quadrilaterals
In the figure, ABCDABCD is a parallelogram. Let EE be a point lying on ADAD such that AE:ED=2:5AE:ED=2:5. CBCB is produced to the point FF such that BF=DEBF=DE. Denote the point of intersection of ABAB and EFEF by GG. It is given that BDBD and CGCG intersect at the point HH. If the area of AEG\triangle AEG is 48 cm248\mathrm{~cm}^{2}, then the area of CDH\triangle CDH is
Figure
A 98 cm298\ cm^{2}
B 343 cm2343\ cm^{2}
C 420 cm2420\ cm^{2}
D 588 cm2588\ cm^{2}
2020 · Paper 2 Q19 Angles and parallel lines
According to the figure, which of the following must be true?

I. uv+w=0 u - v + w = 0^{\circ}

II. u+vw=180 u + v - w = 180^{\circ}

III. u+v+w=450 u + v + w = 450^{\circ}
Figure
A I only
B II only
C I and III only
D II and III only
2020 · Paper 2 Q20 Angles and parallel lines
In the figure, ABCABC is an equilateral triangle and CDECDE is an isosceles triangle with CD=CECD = CE. If DCE=78\angle DCE = 78^{\circ} and ADC=CAD=40\angle ADC = \angle CAD = 40^{\circ}, then CBE=\angle CBE =
Figure
A 1414^{\circ}
B 1919^{\circ}
C 2424^{\circ}
D 2929^{\circ}
2020 · Paper 2 Q21 Pythagoras' theorem
In the figure, ABCDABCD is a rectangle. Let EE be a point lying on ADAD such that BE=8 cmBE = 8\ \text{cm} and CE=15 cmCE = 15\ \text{cm}. If BC=17 cmBC = 17\ \text{cm}, find the area of the rectangle ABCDABCD.
Figure
A 60 cm260\ cm^{2}
B 68 cm268\ cm^{2}
C 120 cm2120\ cm^{2}
D 136 cm2136\ cm^{2}
2020 · Paper 2 Q22 Basic properties of circles
In the figure, ABCDEABCDE is a circle. If AB=10 cmAB=10\text{ cm}, BC=5 cmBC=5\text{ cm}, ABC=90\angle ABC=90^{\circ} and CED=40\angle CED=40^{\circ}, find CDCD correct to the nearest cm\text{cm}.
Figure
A 5 cm5\text{ cm}.
B 6 cm6\text{ cm}.
C 7 cm7\text{ cm}.
D 8 cm8\text{ cm}.
2020 · Paper 2 Q23 Trigonometry
A ship is 5050 km due west of a lighthouse. If the ship moves in the direction S60ES60^{\circ}E, find the shortest distance between the ship and the lighthouse.
A 2020 km.
B 2525 km.
C 4343 km.
D 8787 km.
2020 · Paper 2 Q24 Rectangular coordinate system
The point PP is translated leftwards by 44 units to the point QQ. If the coordinates of the reflection image of QQ with respect to the yy-axis are (5,1)(5,-1), then the polar coordinates of PP are
A (1,45)(1,45^{\circ}).
B (1,225)(1,225^{\circ}).
C (2,45)(\sqrt{2},45^{\circ}).
D (2,225)(\sqrt{2},225^{\circ}).
2020 · Paper 2 Q25 Loci
Let AA be the point of intersection of the straight lines 9x+4y7=09x+4y-7=0 and 9x4y+7=09x-4y+7=0. If PP is a moving point in the rectangular coordinate plane such that the distance between PP and AA is 8, then the locus of PP is a
A circle.
B triangle.
C quadrilateral.
D regular hexagon.
2020 · Paper 2 Q26 Equations of straight lines
The equation of the straight line LL is kx+4y2k=0kx+4y-2k=0, where kk is a constant. If LL is perpendicular to the straight line 6x9y+4=06x-9y+4=0, find the yy-intercept of LL.
A 3-3
B 2-2
C 22
D 33
2020 · Paper 2 Q27 Equations of circles
The equations of the circles C1C_{1} and C2C_{2} are 2x2+2y2+4x+8y149=02x^{2}+2y^{2}+4x+8y-149=0 and x2+y28x20y53=0x^{2}+y^{2}-8x-20y-53=0 respectively. Which of the following is/are true?
A I only
B II only
C I and III only
D II and III only
2020 · Paper 2 Q28 Probability
Two numbers are randomly drawn at the same time from four cards numbered 3, 5, 7 and 9 respectively. Find the probability that the product of the numbers drawn is greater than 3535.
A 12 \frac{1}{2}
B 13 \frac{1}{3}
C 23 \frac{2}{3}
D 38 \frac{3}{8}
2020 · Paper 2 Q29 Measures of dispersion
The bar chart below shows the distribution of the numbers of pens owned by some students. Find the inter-quartile range of the distribution.
Figure
A 1
B 2
C 4
D 6
2020 · Paper 2 Q30 Measures of central tendency
Consider the following integers:

3 3 8 8 10 12 m 12\text{ m } n

Let x, y and z be the median, the mean and the mode of the above integers respectively. If the range of the above integers is 9, which of the following must be true?

I. x=8x = 8

II. y=8y = 8

III. z=8z = 8
A I only
B II only
C I and III only
D II and III only