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Volume, SM-Bank 004 MC

GEOMETRY, FUR1 2008 VCAA 4 MC

The solid cylindrical rod shown above has a volume of 490.87 cm3. The length is 25.15 cm.

The radius (in cm) of the cross-section of the rod, correct to one decimal place, is

  1. \(2.5\)
  2. \(5.0\)
  3. \(6.3\)
  4. \(19.6\)
Show Answers Only

\(A\)

Show Worked Solution

\(V=\pi r^2h\)

\(\text{Where length} =h = 25.15\ \text{cm,}\ V=490.87\ \text{cm}^3\)

\(\therefore\ 490.87\) \(=\pi\times r^2\times 25.15\)
\(r^2\) \(=\dfrac{490.87}{\pi\times 25.15}\)
  \(= 6.2126\dots\)
\(\therefore\ r\) \(= 2.492\dots\ \text{cm}\)
  \(\approx 2.5\ \text{cm (1 d.p.)}\)

 
\(\Rightarrow A\)