# Math Help - measurement problem

1. ## measurement problem

Mr. Dean has provided you with the following diagram. See attached

Calculate the total cost of the semi-circular driveway.

area = piRsq/2 - pirsq/2

I said R = 30
r=14 and I got area =1105. 84 sqft

How do I calculate the volume ?

I have an answer but I don't get it.
V= 1105. 84 x 10/12 ( I don't get the 12) this is for the excavation.

2. Originally Posted by terminator
Mr. Dean has provided you with the following diagram. See attached

Calculate the total cost of the semi-circular driveway.

area = piRsq/2 - pirsq/2

I said R = 30
r=14 and I got area =1105. 84 sqft

How do I calculate the volume ?

I have an answer but I don't get it.
V= 1105. 84 x 10/12 ( I don't get the 12) this is for the excavation.
1. A volume is calculated by $volume = base\ area * height$

2. The base area is measured in squft, the thickness of the construction is measured in inches. You must convert inches into feet to get the volume in cubic feet.

3. As far as I'm informed $1\ foot = 12\ inches~\implies~1\ inch = \frac1{12} \ foot$

4. So $10'' = \left(\frac{10}{12}\right) '$