Question

12 concrete cylindrical pillars of a building are to be covered by aluminum
cladding. Each pillar has a diameter of 70 cm and height of 7m. where the volume of all pillars is 32.28 cubic meters.

1. What is the total lateral surface area of the 12 pillars?
2. If one sheet of aluminum cladding is 1.2m by 2.4m, how many
sheets of aluminum is needed to cover the 12 pillars?

Answer 1

Solution

1.

Lateral surface area of a cylinder is given by the formula;

$A_L = 2\pi rh$

And for the 12 cylinders;

$A_L = 24\pi rh$

$=24×\frac{22}{7}×0.35m ×7m$

$= 184.8 m^2$

2.

In order to find the number of sheets to cover the pillars, we determine the surface area of one sheet (which is in form of a rectangle);

Surface Area of One Sheet $= L × W$

$= 2.4m × 1.2m$

$= 2.88m^2$

Now number of sheets needed $= \frac{184.8m^2}{2.88m^2}$

$=64$ Aluminium Sheets