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AMO 2021 Primary 3 (Grade 3)

Question 1

Ryan is 10th from the front and 10th from the end of a line. How many people are in the line?

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  1. 10
  2. 19
  3. 20
  4. 21
  5. 25

Question 2

Kevin writes every whole number from 1 to 100 once, including both endpoints. How many times does he write the digit 1?

Question illustration
  1. 19
  2. 20
  3. 21
  4. 22
  5. 23

Question 3

Five ears of corn cost 2 dollars. Mom needs 60 ears for a party. How many dollars must she pay?

Question illustration
  1. 15
  2. 20
  3. 24
  4. 25
  5. 30

Question 4

A box with crackers weighs 1 kg. The empty box weighs 50 g. What is the weight of the crackers in grams?

Question illustration
  1. 450
  2. 500
  3. 950
  4. 1050
  5. 1250

Question 5

Jason has seven friends at his birthday party. He cuts a cake into 12 equal slices. Jason and each friend eat one slice. What fraction of the cake is left?

Question illustration
  1. $1/4$
  2. $1/3$
  3. $1/2$
  4. $7/12$
  5. $2/3$

Question 6

Use each digit 0, 3, 6, 8 exactly once to make four-digit numbers, with no leading zero. What is the difference between the greatest and smallest possible numbers?

Question illustration
  1. 8262
  2. 5562
  3. 4950
  4. 3744
  5. 3528

Question 7

A basket has 45 red or green apples. There are twice as many red apples as green apples. How many more red apples are there? In the diagram, R means red and G means green.

Question illustration
  1. 35
  2. 30
  3. 25
  4. 20
  5. 15

Question 8

A rectangular table has area 18 square feet and one side 3 feet long. What is its perimeter in feet?

Question illustration
  1. 9
  2. 18
  3. 21
  4. 22
  5. 25

Question 9

Which numbered shape cannot be made by folding a rectangular sheet of paper once? Interpret the outlines as drawn, so shape 3 is an acute triangle. The supplied answer key has an error, explained in the solution.

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

Question 10

A train leaves Chicago at 9:40 pm and arrives at 2:15 am the following day. How many minutes is the ride?

Question illustration
  1. 215
  2. 240
  3. 255
  4. 275
  5. 290

Question 11

In the multiplication shown, A, B and C are different digits from 0 to 9. What is A + B + C?

Question illustration
  1. 11
  2. 13
  3. 15
  4. 17
  5. 19

Question 12

Cup A contains one and a half times as much water as cup B. Together they contain 1000 ml. How many millilitres are in cup B?

Question illustration
  1. 200
  2. 300
  3. 400
  4. 500
  5. 600

Question 13

The two equalities below use the same values for matching symbols. What is the value of the triangle?

Question illustration
  1. 13
  2. 15
  3. 20
  4. 25
  5. 28

Question 14

The bar graph shows animals on a farm. How many more chickens are needed so that there are three times as many chickens as cows?

Question illustration
  1. 8
  2. 12
  3. 16
  4. 30
  5. 36

Question 15

How many different squares of any size are formed by the lines of the 4 by 4 grid?

Question illustration
  1. 16
  2. 25
  3. 29
  4. 30
  5. 32

Question 16

Find the value of $1+2+4+8+16+32+64+\cdots+512+1024$.

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Question 17

David’s dad is 24 years older than David. How old will David be when his dad is three times his age?

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Question 18

What is the perimeter of the figure in centimetres?

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Question 19

Bob builds the marble shapes shown: 1 marble in the first, 3 in the second, and so on through the tenth shape. How many marbles does he use in total for all ten shapes?

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Question 20

Two rectangles overlap as shown. How many right angles are there in the drawing? Count all right-angle sectors formed by the drawn segments, including those at crossings.

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