Percentages

You need to be able to use basic skills of working with percentages for many different calculations.

Most of these questions will be in a real life context.

Per cent means 'out of one hundred', so \(15\%\) means \(15\) out of \(100\).

\[15\% = \frac{{15}}{{100}}\]

Example

Calculate \(15\%\) of \(\pounds200\)

Answer

\[\frac{15}{100}\times 200= \pounds30\]

Now try the example question below.

Question

Find \(30\%\) of \(\pounds800\).

\[30\% \,of\,\pounds800\]

=\(\frac{30}{100}\times 800\)

\[= \pounds240\]

Question

Find \(17\%\) of \(340kg\)

\(17\%\) of \(340kg\)

= \(\frac{17}{100}\times 340\)

A way of doing this on a calculator is \(340 \div 100 \times 17\).

\[=57.8kg\]

Question

Find \(15\%\) of \(260cm\)

\(15\%\) of \(260cm\)

= \(\frac{15}{100}\times 260\)

One way of doing this on a calculator is \(260\div 100\times 15\).

\[=39cm\]