Use the information provided to calculate the different parts of the proposal: The lazy river is basically a large circle that will need to be filled with water. The radius of the outer perimeter is 30 yards. The river is 4 feet deep and it's width is 5 feet. First compute the river's volume in cubic feet and then calculate how many gallons of water it will hold. Remember 1 cubic foot = 7.48 gallons.

10,995.6 ft^3.

2300.3 gallons.

(both to the nearest tenth).

Step-by-step explanation:

Area of the surface of the river = area of the outer circle - area of the inner circle.

Radius of the outer circle = 30 * 3 = 90 feet.

So the surface area of the river = π (90) ^2 - π (85) ^2

= 875π ft^2

Also the volume of the river = surface area * depth = 875π*4 = 3500π ft^3

= 10,995.6 ft^3.

Number of gallons of water it will hold = 10,995.6 / 4.78

= 2300.3 gallons.