Hi John,

I would first convert the 4 inches to feet. There are 12 inches in a foot so 4 inches is $\frac{4}{12} = \frac13$ feet. Hence the volume of concrete you will need is $1200 \times \frac13 \mbox{ cubic feet. }$ There are 3 feet in a yard and hence there are $3 \times 3 \times 3 = 27$ cubic feet in a cubic yard. Thus if you divide the volume in cubic feet by 27 you will obtain the volume in cubic yards.

Once you have found the volume you can check your answer using our volume calculator.

Penny