The diameter and height of a circular water drum with lid are 6.3 dm and 9.1 dm respectively . Find the cost of painting the outer surface?

Lidare

Go on line. Search for "surface area of a cylinder", find the formula. Use it, them multiply the answer by 0.60

First you will have to find the surface area of the waterdrum.

For the top face of the drum we need to do pi*(3.15^2) =31.17 as the area of the circle is pi*r^2 and the radius is 0.5 of the diameter
As the bottom of the drum is equal to the top we will double this answer to get 62.34

Now we need to work out the final face of the drum, which is around the drum. To find this we need the circumfrance of the top face * height.

The circimfrance is pi*diameter, so 6.3*pi = 19.79
Now we need to times this by the height, 19.79 * 9.1 = 180.09

Now to find the whole surface area we add 62.34 to 180.09 = 242.43
As we know the surface area we can finish the question off by doing 242.43 * 0.6 = 145.46

Hope this helped :)

The process is:
1. Calculate the area in square dm.
2. Multiply by the cost per square dm.

The surface area of a cylinder is 2pi*r*h for the sides, and 2*pi*r^2 for the top and bottom.