PL RU P2L16 Guess and Check WS

Primary 2

Rev Up! Math

Name Heuristics: Drawing a Diagram/Guess and Check (Lesson 16)
Tutor
Topic

Heuristics: Drawing a Diagram/Guess and Check (Lesson 16)

Primary 2: Rev Up! Math

1. Mr Sim sells some bicycles and tricycles.
There are 11 bicycles and tricycles for sale at the moment.
The total number of wheels is 27.
(a) How many bicycles are for sale?
(b) How many tricycles are for sale?

Method 1: Draw a Diagram

Step 1: Draw 11 circles to represent 11 bicycles and tricycles.

Step 2: Assume all are bicycles. Draw 2 wheels for each bicycle.

Step 3: How many more wheels do we need? Adjust your diagram accordingly.

Method 2: Guess and Check Table

Number Number of Number Number Total Check
of Wheels of of Wheels Number of

Bicycles Tricycles Legs

(a) There are bicycles.

(b) There are tricycles. 1

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Primary 2: Rev Up! Math

2. A waveboard has 2 wheels.
Askateboard has 4 wheels.
Mr Jo bought 9 waveboards and skateboards as Christmas presents for his
nieces and nephews.
There were 32 wheels in total.
(a) How many waveboards did he buy?
(b) How many skateboards did he buy?

Method 1: Draw a Diagram

Step 1: Draw 9 rectangles to represent the waveboards and skateboards.

Step 2: Assume all are waveboards. Draw 2 wheels for each wave board.

Step 3: How many more wheels do we need? Adjust your diagram accordingly.

Method 2: Guess and Check Table

Number of Number of Number Number of Total Check
Waveboards
Waveboard of Skateboard Number
Wheels Skate- Wheels of
boards
Wheels

(a) He bought waveboards.

(b) He bought skateboards. 2

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Primary 2: Rev Up! Math

3. A pair of spectacles has 2 lenses.
Amonocle has only 1 lens.
A scientist bought a total of 18 spectacles and monocles.
There were 31 lenses altogether.
(a) How many spectacles did the scientist buy?
(b) How many monocles did the scientist buy?

Use the Guess and Check table below to solve the problem.

Number Number Number Number Total Check
of of of of Number of

Spectacles Spectacle Monocles Monocle Lenses

(2 lenses) Lenses (1 lens) Lenses

(a) The scientist bought pairs of spectacles.
(b) The scientist bought monocles.

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Primary 2: Rev Up! Math

4. Apen costs $2 and a notebook costs $4.
Harry paid $20 for 6 notebooks and pens.
(a) How many pens did Harry buy?
(b) How many notebooks did Harry buy?

Use the Guess and Check table below to solve the problem.

Number Cost Number Cost

of of of of Total Cost Check
Pens Pens
Notebooks Notebooks

(a) Harry bought pens.
(b) Harry bought notebooks.

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Primary 2: Rev Up! Math

5. There were some peacocks and deer in an enclosure of a zoo.
Megan counted 7 heads and 24 legs altogether.
(a) How many peacocks were there?
(b) How many deer were there?

Use the Guess and Check table below to solve the problem.

Number Number of Number Number of Total Check
of Peacock of Deer Number of

Peacocks Legs Deer Legs Legs

(a) There were peacocks.
(b) There were deer.

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Primary 2: Rev Up! Math

6. James formed triangles and squares using toothpicks.
He used a total of 47 toothpicks.
(a) How many triangles did he make?
(b) How many squares did he make?

Use the Guess and Check table below to solve the problem.

Number Number of Number Number of Total Check
of Toothpicks of Toothpicks Number of
Toothpicks
Triangles Used for Squares Used for
Triangles Squares Used

(a) He made triangles.
(b) He made squares.

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Primary 2: Rev Up! Math

7. Dad bought 7 go-pros for a recent trip.
The waterproof go-pros cost $30 each and the non waterproof
ones cost $20 each. Dad paid $150 in total.
(a) How many waterproof go-pros did Dad buy?
(b) How many non-waterproof go-pros did Dad buy?

Use the Guess and Check table below to solve the problem.

Number Cost of Number Cost of Total Cost Check
of Waterproof of Non-

Waterproof Go-pros Non- waterproof
Go-pros Go-pros
waterproof

Go-pros

(a) Dad bought waterproof go-pro/s.

(b) Dad bought non-waterproof go-pro/s.

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Primary 2: Rev Up! Math

8. Si Hui spotted 9 spiders and ladybugs in her garden.
She counted a total of 60 legs in all.
(a) How many spiders were there?
(b) How many ladybugs were there?

Draw a Guess and Check table in the space provided below to solve the
problem.

(a) There were spiders.

(b) There were ladybugs.

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Primary 2: Rev Up! Math

9. Mrs Tay packs some stickers into 16 goody-bags.
Some goody-bags have 2 stickers each and others
have 3 stickers each.
Mrs Tay packs a total of 39 stickers.
(a) How many bags contain 2 stickers?
(b) How many bags contain 3 stickers?

Draw a Guess and Check table in the space provided below to solve the
problem.

(a) bags contain 2 stickers.

(b) bags contain 3 stickers.

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Primary 2: Rev Up! Math

10. Miss Lee bought 10 cupcakes for $38.
She bought at least one of each type of cupcake shown below.

Type of Cupcake Price

$5

$3

(a) How many chocolate chip cupcakes did Miss Lee buy?
(b) How many strawberry cupcakes did Miss Lee buy?
Draw a Guess and Check table in the space provided below to solve the
problem.

(a) Miss Lee bought chocolate chip cupcakes.

(b) Miss Lee bought strawberry cupcakes.
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Primary 2: Rev Up! Math

11. Mrs Ho bought lunch for her 4 friends.
Each of her friends picked either a salad or a bowl of noodles.
The salads cost $9 each and the bowls of noodles cost $6 each.
If Mrs Ho spent $27, how many salads did she buy?

Mrs Ho bought salad/s.

12. Flora Gardening Store sells clay flower pots and ceramic flower pots, which
hold 9 litres of soil and 3 litres of soil respectively. Lisa bought 7 flower pots,
which hold a total of 51 litres of soil. How many clay flower pots did she buy?

She bought clay flower pots.
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