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AIMO 2021 Primary 3 — Preliminary (Open Trial 1)

Question 1

A tree is planted at every 10 meters along a stretch of road. If the stretch of road is 150 m long and the trees are planted at opposite ends of the road, how many trees are there?
  1. 12
  2. 14
  3. 15
  4. 16

Question 2

Calculate 37 × 98

Printed options: A: 326; B: 326; C: 346; D: 186.
Editorial response convention: give the correct value; none of the printed options is correct.

Question 3

Find the value of 3 + 5 + 7 + 9 + 11 + 13 + 15
  1. 45
  2. 60
  3. 63
  4. 16

Question 4

Given the number sequence : 1 2 3 4 1 2 3 4 1 2 3 4 ……

What is the 35th number?
  1. 1
  2. 2
  3. 3
  4. 4

Question 5

Alexa is picking her activities for this year. She wants to play one sport and join one club. The sports she can play are football and volleyball. The clubs she is considering are the drama club and the math club. How many different combinations of activities can Alexa pick
  1. 4
  2. 5
  3. 6
  4. 7

Question 6

If a∗b = a×b+a−b, find the value of (5∗3)*2.
  1. 32
  2. 30
  3. 40
  4. 49

Question 7

Find the value of 26 × 5 × 8 × 125.
  1. 13005
  2. 130000
  3. 13000
  4. 12450

Question 8

How many squares are there in the following figure?

Question illustration
  1. 10
  2. 11
  3. 12
  4. 15

Question 9

Find the ones digit in 24 × 24 × 24 × … × 24 ( 24 numbers 24)

Printed options: A: 6; B: 4; C: 2; D: 6.
Editorial response convention: give the correct value or either matching printed letter.

Question 10

The perimeter of the following figure is 24 cm. What is its area in square centimeters?

Question illustration
  1. 18
  2. 20
  3. 24
  4. 26

Question 11

2021 = 2 × 1000 + ⋯× 10 + 1

What is the missing number?
  1. 200
  2. 20
  3. 0
  4. 2

Question 12

During a shopping trip, Sally spent half of her money in the first shop. She spent \$2 more than half of her remaining money in the second shop. She was left with \$30 in the end. How much money did Sally have at first?

Printed options: A: 128; B: 120; C: 140; D: 128.
Editorial response convention: give the correct value or either matching printed letter.

Question 13

A wire of length 84 cm is used to make a square of side 8 cm. The remaining wire is then used to make a rectangle of breadth 10 cm. What is the length of rectangle?
  1. 18
  2. 12
  3. 10
  4. 16

Question 14

A dance class has 9 boys and 11 girls. How many ways can the teacher choose a couple consisting of 1 boy and 1 girl to perform the chicken dance?
  1. 30
  2. 80
  3. 99
  4. 90

Question 15

Calculate 120 −117 + 116 −113 + 112 −109 + ⋯+ 100 −97.
  1. 10
  2. 18
  3. 14
  4. 12

Question 16

There are five children A, B, C, D and E. Below are some information about them.

Anna is older than Bella

Chris is younger than [name missing in source] but older than Don

Don is older than Bella

Emma is younger than Anna .

Who is the youngest children?
  1. Anna
  2. Bella
  3. Chris
  4. Don

Question 17

What are the missing number in the number pattern below?

Answer : ……………………………

Question illustration

Question illustration

Question 18

A rabbit has 18 carrots. She eats 3 carrots everyday. She ate 9th carrot on Thursday. On which day did she start eating the carrots?

Answer : ……………………………

Question 19

Given 2 △ 3 = 2 + 4 + 5

2 △ = 2 + 3 + 4 + 5

Find the value of 6 △ 3.

Answer : ……………………………

Question 20

Two similar books and three identical pencil boxes cost \$42. Two similar books and six identical pencil boxes cost \$60. How much does each pencil box cost?

Answer : ……………………………