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SEAMO 2027 - Paper C - SET 11 - Self-study

Question 1

SEAMO self-study edition 2027; not an official 2027 paper. Original source years are retained. 25 questions, 90 minutes; Q1–10: 3 points, Q11–20: 4 points, Q21–25: 6 points, total 100. Original response types and all subparts are preserved. Verified is an editorial convention; source defects, necessary assumptions and unresolved mathematical uncertainty are disclosed.

Find the last two digits of $6^{2015}+(2015\times6)+2015^6$.

Question 2

A new operation is defined by $m*n=m^n$. Find $n$ if $n*5=243$.
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5

Question 3

Find $\dfrac1{1\times2}+\dfrac1{2\times3}+\cdots+\dfrac1{2018\times2019}+\dfrac1{2019\times2020}$.

Question 4

Candle A takes 3 hours to burn completely. A shorter candle B, with a larger diameter, takes 5 hours. They are lit at the same time and have equal heights 2 hours later. What was their initial height ratio A : B?

Practice assumption: each candle loses height at a constant rate until it burns out. The source leaves this usual candle-model assumption implicit. Enter a simplified ratio in the exact form a:b or a : b (one space on each side of the colon). Other written forms are unsupported by the offline exact-text check and remain ungraded pending manual review.

Question 5

The graph shows the minutes Mark and Peter spent in Taekwondo training during one week. On average, how many more minutes per day did Peter train than Mark?

Question illustration
  1. 0
  2. 1
  3. 2
  4. 3
  5. 4

Question 6

Ten identical circles are arranged as shown. The straight line $AB$ passes through the centres of two circles. What is the ratio of the area of the circles above $AB$ to their area below $AB$?

Question illustration
  1. 2:7
  2. 2:3
  3. 7:13
  4. 9:11
  5. None of the above

Question 7

A pentagon has side length 10 cm. Five identical circles are drawn with the five vertices as centres, as shown. Find the shaded area in $\text{cm}^2$. Use $\pi=3.14$.

Diagram convention: adjacent circles are externally tangent along the pentagon’s sides, and the shaded parts are the non-overlapping sectors inside the pentagon. These conditions are depicted but not stated explicitly in the source.

Question illustration
  1. 98.80
  2. 106.80
  3. 117.75
  4. 138.50
  5. 154.40

Question 8

Find the difference between the total area of the three squares and the total area of the four triangles in the figure, in $\text{cm}^2$.

Question illustration

Question 9

Paul walks from A to B at 80 m/min while Mary starts at the same time from B to A at 60 m/min. They meet 120 m from the midpoint of AB. If Paul stops for a break along the way, they would still meet 120 m from the midpoint of AB. How long is the break, in minutes?

Practice interpretation: the break is positive and is taken before they meet; Mary continues walking at her stated speed. Otherwise a break after meeting would not be determined by the meeting point.

Question 10

Given $m+m=a$, $m-m=b$, $m\times m=c$, $m\div m=d$, and $a+b+c+d=256$, find $m$.

Choose from the five printed options. The equations alone may have a value outside that list.
  1. 12
  2. 13
  3. 14
  4. 15
  5. 16

Question 11

$BDEF$ is a square inside right-angled triangle $ABC$, as shown. Given $AE=10$ cm and $EC=15$ cm, find the shaded area, in $\text{cm}^2$.

Question illustration
  1. 65
  2. 70
  3. 75
  4. 80
  5. 120

Question 12

A triangle has whole-number side lengths and perimeter 27 cm. How many such triangles are possible?
  1. 17
  2. 18
  3. 19
  4. 20
  5. 21

Question 13

There are fifty 1-dollar, 2-dollar and 5-dollar notes. There are two more 1-dollar notes than 2-dollar notes. The total value is 116 dollars. How many 5-dollar notes are there?
  1. 9
  2. 10
  3. 11
  4. 12
  5. 13

Question 14

Find $*\times36$, given $\left[13.5\div\left(11+\dfrac{*}{1-\dfrac1{10}}\right)-1\div7\right]\times1\dfrac16=1$.
  1. 57
  2. 64
  3. 71
  4. 81
  5. 91

Question 15

Find $\angle a+\angle b+\angle c+\angle d+\angle e+\angle f+\angle g$.

Question illustration
  1. $150^\circ$
  2. $180^\circ$
  3. $360^\circ$
  4. $540^\circ$
  5. $720^\circ$

Question 16

$ABCD$ is a square of side 6 cm. Points $E$ and $F$ lie on $BC$ and $DC$ respectively, with $BE=2CE$ and $DF=2CF$. Find the shaded area, in $\text{cm}^2$.

Question illustration

Question 17

A locker passcode is a three-digit number. Three people make these guesses: A: 954; B: 358; C: 214. Each person has exactly one correct digit. Which of the following could be the passcode?
  1. 954
  2. 254
  3. 258
  4. 918
  5. 914

Question 18

In the quadrant shown, consider (i) $A=28\text{ cm}^2$; (ii) $A=30\text{ cm}^2$; (iii) $A=B$; (iv) $A>B$. Which statements are correct? Use $\pi=22/7$.

Diagram convention: the two inner arcs are semicircles whose diameters are the two 14 cm radii of the outer quadrant.

Question illustration
  1. (i) and (iii)
  2. (ii) and (iii)
  3. (i) and (iv)
  4. (ii) and (iv)
  5. (iii) and (iv)

Question 19

Each Grade A durian costs 12 dollars and each Grade B durian costs 22 dollars. Mr Tan pays 126 dollars for some Grade A and Grade B durians. How many Grade A durians does he buy?
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5

Question 20

A farm has 120 chickens and rabbits altogether. The chickens have 6 more legs in total than the rabbits. How many rabbits are there?