Volume, SM-Bank 156

A right cylinder has a volume of \(10\ 178.76\) cubic centimetres. Calculate the radius of the cylinder if the height is 10 centimetres.

Give your answer to the nearest whole centimetre. (2 marks)

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\(18\ \text{cm}\)

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\(V\)	\(=\pi r^2h\)
\(10\ 178.76\)	\(=\pi\times r^2\times 10\)
\(10\ 178.76\)	\(=10\pi\times r^2\)
\(r^2\)	\(=\dfrac{10\ 178.76}{10\pi}\)
\(r^2\)	\(=323.999\dots\)
\(r\)	\(=\sqrt{323.9999}=17.999\dots\)
\(r\)	\(\approx 18\ \text{cm (nearest whole centimetre)}\)

\(\therefore\ \text{The radius of the cylinder is approximately 18 cm}\)