Question

A metal cylinder has height of 7m. The inner radius of cylinder is 1 m and outer radius is 1.5 m. Calculate

1) Inner surface area

2) Outer surface area

3) Total surface area . (Take pi=$\frac{22}{7}$) [4 MARKS]

Answer 1

Concept: 1 Mark
Application: 1 Mark each

$h=7,r_{inner}=1,r_{outer}=1.5$

1) Inner surface area
$=2\pi r_{inner}h$

$=2\times \frac{22}{7}\times 1\times 7$

$=44m^2$


2) Outer surface area
$=2\pi r_{outer}h$

$=2\times \frac{22}{7}\times 1.5\times 7$

$=66m^2$


3) Total surface area
$=2\pi rh+2\pi r_{outer}h+2\pi (r_{outer}^2-r_{inner}^2)$

$=44+66+7.853$

$=117.8539m^2$