Question

What is the surface area of a cylinder that has a top and bottom if the height is $8.5$ units and the diameter is $3$ units?

• A. $18\pi$ square units
• B. $30\pi$ square units
• C. $32\pi$ square units
• D. $36\pi$ square units
• E. $54\pi$ square units

Answer 1

Answer: (B)

$30\pi$ square units

Given: height $=8.5$, diameter $=3$
$\therefore$ radius $=$ $\frac{D}{2}=\frac{3}{2}=1.5$
Surface area $=$ $2\pi rh+2\pi r^2$
$=2\pi \times 1.5\times 8.5+2\pi \times {1.5}^2$
$=2\pi (12.75+2.25)$
$=2\pi \left(15\right)$
$=30\pi$ sq.units