Question

Question #cd663

Answer 1

`115` pots can be painted completely

Explanation:

The first problem you should see is that there are two different units.
`m^2 and cm`

Converting units of area is more tricky than just lengths, so let's change `cm` to `m` right at the beginning. For `cm rarr m, div 100`

`"radius " = 15cm = 0.15m and "height "20cm = 0.2m`

Once we know the surface area of 1 pot, we can just divide `30m^2` by that answer to find how many of the same pots can be painted.

Each pot has a base ( a circle) and the curved part.
You should know those formulae
Circle Area =`pir^2` Curved surface area = `2pirh`

Total outside area of one pot =`pir^2 + 2pirh`

`SA=pi(0.15)^2 +2pi(0.15)(0.2)`
`SA =0.0225pi +0.06pi`
`SA = 0.0825pi" "m^2" "larr` leave it in terms of `pi` for now

How many pots can be painted? Divide 30 by the area of one pot.

`30/(0.0825pi) = 115.749`

Now be careful... Although the first decimal is more than 5, do not round up...

This means that 115 pots can be painted completely but only about `3/4` of the next pot gets done.