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Mathematics

Percentages

Educator section

Memorandum

  • (i) 23 909 920
  1. 42 840 000
  2. 320

15.3.1

a) R31,04

b) 15 mm

15.3.2

a) R525

b) R3,00

c) 8,25 kg

d) R12,69

16.3

a) 25%

b) 8, 3 . size 12{ {3} cSup { size 8{ "." } } } {} %

c) 70%

d) 37,5%

e) 80%

f) 66, 6 . size 12{ {6} cSup { size 8{ "." } } } {} %

Leaner section

Content

Acticity: how to calculate a percentage of an amount [lo 1.7.6, lo 1.9.2, lo 2.7.1 ]

a) Work together with a friend. Can you calculate the answers with the help of a calculator?

(i) How many people live in rural areas?

(ii) How many votes did the ANC get?

(iii) How many patients were heavy smokers?

b) How did you calculate the answers?

15.2.1 REMEMBER!

To calculate the percentage of an amount:

a) Write the percentage as a fraction with the denominator 100 ORWrite the percentage as a decimal fraction

b) Multiply this fraction / decimal fraction with the amount / number / quantity that is given

In the example above:

58 = 58 100 size 12{"58"%= { { size 8{"58"} } over { size 8{"100"} } } } {}

58 100 × 41 224 000 1 58 41 224 000 100 = 23 909 920 people alignl { stack { size 12{ { { size 8{"58"} } over { size 8{"100"} } } times { { size 8{"41"`"224"`"000"} } over { size 8{1} } } } {} #= { { size 8{"58"`` size 10{ times }``"41"`"224"`"000"} } over {"100"} } {} # size 12{ {}="23"`"909"`"920"` ital "people"} {}} } {} OR 

15.2.2 Remember also!

With a calculator: multiply 41 224 000 by 58 %

You will thus key in: 58 ÷ 100 × 41 224 000 =

OR

58% × 41 224 000 =

15.3.1 Calculate the following without a calculator:

  1. 25% of R124, 16

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b) 50% of 30 mm

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15.3.2 Use your calculator and calculate:

  1. 15% of R3 500

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b) 12% of 25

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c) 37,5% of 22 kg

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d) 75% of R16,92

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16. One amount as a percentage (%) of another amount

16.1 Work together with a friend. Look carefully at the following problem and the solution.

Top Teenage T-shirts printed 120 T-shirts. 72 were sold immediately. What % of the T-shirts were sold?

72 % of the 120 T-shirts were sold : thus 72 120 size 12{ { { size 8{"72"} } over { size 8{"120"} } } } {} % means something out of 100

Thus: 72 120 × 100 1 size 12{ { { size 8{"72"} } over { size 8{"120"} } } times { { size 8{"100"} } over { size 8{1} } } } {} =60%

16.2 REMEMBER!

To calculate % of amounts:

a) Convert first to the same unit

b) Express the given amounts as a fraction :

amount (in the same unit!)
other amount

c) Multiply it by 100

16.3 Calculate how much % the first amount is of the second amount (you may use your calculator):

a) 120 of 480

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b) 23 of 276

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c) 3 500 ml of 5 litre

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d) 750 g of 2 kg

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e) 4 out of 5 for a test

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f) 2 out of balle

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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 that involve:

1.7.6 finding percentages;

Assessment Standard 1.9: We know this when the learner uses a range of techniques to perform calculations including:

1.9.2 using a calculator.

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.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Mathematics grade 7. OpenStax CNX. Sep 16, 2009 Download for free at http://cnx.org/content/col11075/1.1
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