\(\text{25}\%\) of \(\text{R}\,\text{124,16}\)
\(\text{25}\% = \frac{\text{1}}{\text{4}}\). \(\frac{\text{1}}{\text{4}} \text{ of } \text{R}\,\text{124,16} = \text{R}\,\text{124,16} \div \text{4} = \text{R}\,\text{31,04}\)
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Let's see how this works in an example.
Use a calculator to answer the following questions:
How many people live in rural areas?
How many T.B. patients are H.I.V. positive?
How many people had never voted before the 1994 election?
Top Teenage Tshirts printed \(\text{120}\) Tshirts. They sold \(\text{72}\) Tshirts immediately. What percentage of the Tshirts were sold?
\(\text{72}\) of the \(\text{120}\) Tshirts were sold
\(\text{72} \div \text{120} \times \text{100} = \text{60}\%\). So \(\text{60}\%\) of the Tshirts were sold.
Calculate the following without a calculator:
\(\text{25}\%\) of \(\text{R}\,\text{124,16}\)
\(\text{25}\% = \frac{\text{1}}{\text{4}}\). \(\frac{\text{1}}{\text{4}} \text{ of } \text{R}\,\text{124,16} = \text{R}\,\text{124,16} \div \text{4} = \text{R}\,\text{31,04}\)
\(\text{50}\%\) of \(\text{30}\) \(\text{mm}\)
\(\text{50}\% = \frac{\text{1}}{\text{2}}\). \(\frac{\text{1}}{\text{2}} \text{ of } \text{30}\text{ mm} = \text{30}\text{ mm} \div \text{2} = \text{15}\text{ mm}\)
Using your calculator and calculate:
\(\text{15}\%\) of \(\text{R}\,\text{3 500}\)
\(\text{R}\,\text{525}\)
\(\text{12}\%\) of \(\text{25}\) litres
\(\text{3}\) litres
\(\text{37,5}\%\) of \(\text{22}\) \(\text{kg}\)
\(\text{8,25}\) \(\text{kg}\)
\(\text{75}\%\) of \(\text{R}\,\text{16,92}\)
\(\text{R}\,\text{12,69}\)
\(\text{18}\%\) of \(\text{105}\) \(\text{m}\)
\(\text{18,9}\) \(\text{m}\)
\(\text{79}\%\) of \(\text{840}\) \(\text{km}\)
\(\text{663,6}\) \(\text{km}\)
Calculate what percentage the first amount is of the second amount (you may use your calculator):
\(\text{25}\%\)
\(\text{8,3}\%\)
\(\text{70}\%\)
\(\text{37,5}\%\)
\(\text{90}\%\)
\(\text{14,3}\%\)
Look at the following extracts from newspaper articles and adverts:
The price of a tub of margarine is \(\text{R}\,\text{6,99}\). If the price rises by \(\text{10}\%\), how much will it cost?
New price is \(\text{R}\,\text{6,99}\) + \(\text{10}\%\) of \(\text{R}\,\text{6,99}\)= \(\text{R}\,\text{6,99}\) + \(\text{70}\) \(\text{c}\) (rounded off) = \(\text{R}\,\text{7,69}\) OR New price is (\(\text{100}\) + \(\text{10}\))\% of \(\text{R}\,\text{6,99}\) = \(\text{110}\%\) of \(\text{R}\,\text{6,99}=\frac{\text{110}}{\text{100}} \times \frac{\text{6,99}}{\text{1}}= \text{R}\,\text{7,69}\) (rounded off)
Top Teenage Tshirts have a \(\text{20}\%\) discount on all Tshirts. If one of their Tshirts originally cost \(\text{R}\,\text{189,90}\), what will you pay for it now?
You only pay \(\text{80}\%\) (\(\text{100}\%\) \(\) \(\text{20}\%\) discount). Thus: \(\frac{\text{80}}{\text{100}} \times \text{189,901} = \text{R}\,\text{151,92}\) OR \(\text{20}\%\) of \(\text{R}\,\text{189,90} = \frac{\text{20}}{\text{100}} \times \text{189,901}\). The discount is thus \(\text{R}\,\text{37,98}\). You pay \(\text{R}\,\text{189,90}  \text{R}\,\text{37,98} = \text{R}\,\text{151,92}\).
Look at the pictures below. What is the value of each of the following items, in rands?
\(\text{R}\,\text{239,96}  \text{R}\,\text{59,75} = \text{R}\,\text{180,21}\)
\(\text{R}\,\text{299,50}  \text{R}\,\text{44,925} = \text{R}\,\text{1 254,58}\)
\(\text{R}\,\text{9 875} + \text{R}\,\text{790} = \text{R}\,\text{10 665}\)
\(\text{R}\,\text{15 995} + \text{R}\,\text{799,75}= \text{R}\,\text{16 794,75}\)
Calculate the percentage discount on each of these items:
\(\frac{\text{R}\,\text{1 360}}{\text{R}\,\text{1 523}} = \text{89}\%\). So discount is \(\text{100}\%  \text{89}\% = \text{11}\%\)
\(\frac{\text{R}\,\text{527,40}}{\text{R}\,\text{586}} = \text{90}\%\). So discount is \(\text{100}\%  \text{90}\% = \text{10}\%\)
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