Andy wants to build a circular concrete patio in his backyard and install a jungle gym on top of it. one 80-lb bag of concrete will be enough for 2 square feet. if he wants the diameter of the patio to be 10 ft, how many bags of concrete will he need to purchase?

For this case, the first thing you should do is calculate the area of the circle.

We have then:

Where,

r: radius of the circle

Substituting values we have:

Then, to find the number of concrete balls, we can make the following rule of three:

1 bag > 2 square feet

x > 78.5 square feet

From here, we clear the value of x:

Rounding to the nearest whole number we have:

he will need to buy 40 bags of concrete

it is x=-4

step-by-step explanation:

this may not be at all, but i use the same website you're using for school, and if i'm stuck doing one of these i try to look for it on the section.