3.9 Percentages – discount and increases

Mathematics

Percentages

Educator section

Memorandum

17.4

a) R179,97

b) R254,58 (rounded off)

c) R10 665

d) R16 794,75

17.5.2

a) 10,7%

b) 10%

Leaner section

Content

Activity: percentages – discount and increases [lo 1.7, lo 2.7.1]

17. PERCENTAGES – DISCOUNT AND INCREASES

17.1 Look at the following advertisements

17.2 Did you know?

COST PRICE : The amount that the dealer / trader / merchant pays for an article

MARKED PRICE : This is the price of the article

SELLING PRICE : This is the price after discount

PROFIT : Sale price – cost price

17.3 Work together with a friend through the following problem and solutions:

(i) The price of a tub of margarine is R6,99. If the price is going to rise by 10 %, how much will you have to pay for the margarine in the future?

a) New price is R6,99 + 10% of R6,99= R6,99 + 70 c (rounded off)= R7,69

b) New price is (100 + 10)% of R6,99

= 110% of R6,99

= R7,69 (rounded off)

Which method do you choose? ..................................................

Why? ……………………………………………………………………………

(ii) Top Teenage T-shirts have a 20 % discount on all T-shirts. If the T-shirt originally cost R189,90, what will you pay for it now?

a)

I only pay 80% (100% - 20% discount)

Thus: $\frac{\text{80}}{\text{100}}\times \frac{\text{189},\text{90}}{1}$

= R 151, 92

b)

20% of R189,90 = $\frac{\text{20}}{\text{100}}\times \frac{\text{189},\text{90}}{1}$

The discount is thus R37,98

I pay R189,90 – R37,98 = R151,92

Which method do you choose? ..................................................

Why?

17.4 What will you pay for the following items?

17.5.1 Important to remember!

17.5.2 Divide into groups of three. Can you calculate how much % discount was given on the following items?

17.5.3 Explain your method(s) to the rest of the class.

Assessment

Learning Outcome 1: The learner will be able to recognise, describe and represent numbers and their relationships, and to count, estimate, calculate and check with competence and confidence in solving problems.

Assessment Standard 1.7: We know this when the learner estimates and calculates by selecting and using operations appropriate to solving problems;

Learning Outcome 2: The learner will be able to recognise, describe and represent patterns and relationships, as well as to solve problems using algebraic language and skills.

Assessment Standard 2.7: We know this when the learner determines, analyses and interprets the equivalence of different descriptions of the same relationship or rule presented:

2.7.1 verbally.