Question

My answer is somehow wrong…

How am I supposed to answer this correctly? Pls someone tell me the answer to the number of gallons of coating I need!

Answer 1

i think answer is 20.028 yard

Explanation:

it comes after putting whole value of pie and minusing .just like you have done

Answer 2

21 gallons of coating

Explanation:

In order to find out how many gallons of coating we need to cover the ring-shaped path around the pool, we can calculate the area of the ring and then divide it by the coverage per gallon.

Calculate the area of the outer circle:

`\sf A_(outer) = \pi \textsf{ (outer radius)}^2`

`\sf A_(outer )= \pi \cdot (10 yd)^2`

`\sf A_(outer ) = 100\pi yd^2`

Calculate the area of the inner circle:

`\sf A_(inner) = \pi \textsf{ (inner radius)}^2`

`\sf A_(inner) = \pi \cdot (7 yd)^2`

`\sf A_(inner) = 49 \pi yd^2`

Now,

Calculate the area of the ring-shaped path by subtracting the inner circle's area from the outer circle's area:

`\sf A_(ring) = A_(outer )- A_(inner)`

`\sf A_(ring) = 100\pi yd^2 49 \pi yd^2`

`\sf A_(ring )= 51 \pi yd^2`

And finally calculate how many gallons of coating are needed to cover the ring-shaped path:

`\sf Gallons_(needed) = \frac{A_(ring) }{ \textsf{Coverage per gallon}}`

We do have:

• Coverage per gallon = 8 yd² per gallon
• Area of ring = 51π yd²

Substituting value:

`\sf Gallons_(needed) =\frac{51\pi yd^2 }{8 yd^2 \textsf{ per gallon}}`

`\sf Gallons_(needed )\approx 20.03 gallon`

Since the 20 gallon is little less to complete for the coating, we need 21 gallons of coating.

We would need approximately 21 gallons of coating to cover the ring-shaped path around the pool.