3.2 Selection and computations

1. The following activity is for your portfolio.

Look carefully at the assessment table before you begin – your teacher will allocate a code from 1 - 4 for the different sections.

Challenge!

1.1 Carry out a survey in your class and find out how many learners read which magazines. Write you information down in a table, e.g.

1.2 Now show the information by means of a pie diagram.

1.3 Answer the following questions:

a) Which magazine is the most popular?

b) Which magazine is read the least?

c) Which magazine is YOUR favourite?

Why?

BRAIN–TEASER!

Who am I?

a) If you subtract me from $\frac{1}{2}$ , you will get $\frac{3}{8}$

b) If you cut me into sixths, you will have $\frac{\text{24}}{6}$

c) If you double me, you will get 4 $\frac{1}{2}$

1. If you halve me, you will get $2\frac{1}{\text{12}}$
2. If you calculate $\frac{3}{4}$ of me, you will get 12

Activity 5:

To solve problems in context [lo 1.6.1]

Split up into groups of three. You will be given the necessary paper to work on. Remember to discuss the solutions amongst yourselves beforehand and then you can do them neatly on paper.

1. Mrs Mvusi buys 7 metres of material. If she wants to make each one of her four children a bright cushion for his or her room, how many metres of material can she use for each one? (All the cushions are of the same size.) Give each answer as a fraction.

2. Mr Muruvan buys 9 pieces of dry sausage that he wants to share equally among himself, his wife and their five children. What fraction of the sausage will each one get?

3. Grandpa Ben would like to divide R30 equally among his four grandchildren. What is the amount each one will get?

a) Did she divide it fairly?

b) What fraction does each person get?

c) Write your answer as an improper fraction:

1.3 Sketch the solutions to the following:

a) Divide eight fizzers equally between five children.

b) Divide five milk tarts equally between 12 guests.

1.4 Calculate the following:

a) Divide R5,00 equally between four children.

b) Divide 13 pies equally between eight learners.

Activity 6:

To use a series of techniques to do calculations [lo 1.10.5]

1. It is important for us to know how to key in ordinary fractions on a pocket calculator. This will help us find the answers to problems in no time.

Did you know?

If you want to show a fraction on the calculator, e.g. $\frac{5}{7}$ you must key in 5 ÷ 7 = .

1.1 How does the calculator show the following fractions? Write down what you key in.

a) $\frac{3}{5}$ ______________

b) $\frac{6}{7}$ ______________

c) $\frac{5}{8}$ ______________

d) $\frac{1}{\text{12}}$ ______________

e) $\frac{3}{4}$

BRAIN–TEASER!

There are seven cows in a camp. Isolate them by means of three fences so that each cow is in its own small camp.

Indicate with a coloured pencil crayon where you would put the fences.

Assessment

Memorandum

ACTIVITY 1

1. 1.1 $\frac{1}{8}$ 1.2 $\frac{3}{\text{12}}$ = $\frac{1}{4}$

1.3 $\frac{3}{\text{12}}$ = $\frac{1}{4}$ 1.4 $\frac{6}{\text{10}}$ = $\frac{3}{5}$

1.5 $1\frac{5}{\text{10}}$ = $1\frac{1}{2}$ 1.6 $1\frac{3}{8}$

ACTIVITY 2

1. It is the same

2. 10 ; 5

7.1: 21

7.2; 20

• :300

7.4 :168

ACTIVITY 3

1. 1.1: 200 ml

1.2: 1 500 m

1.3: 300 g

1.4; $\frac{5}{6}$

1.5: 2 500 mm or 2,5 m or 2 $\frac{1}{2}$ m

BRAIN-TEASER!

a) $\frac{1}{8}$

1. 4
2. 2 $\frac{1}{4}$
3. 4 $\frac{1}{6}$
4. 16

1.4 a) R1,25 / 125c

1. 1 $\frac{5}{8}$

ACTIVITY 7

1.1 a) 3 $$ 5 = 0,6

1. 6 $$ 7 = 0,8571428
2. 5 $$ 8 = 0,625
3. 1 $$ 12 = 0,0833333
4. 3 $$ 4 = 0,75