The outside diameter of a flywheel rim is 3 1/2 feet. The inside diameter of the rim is 2 feet 10 inches. Find the area of the rim to the nearer hundredth square inch.

  477.52 square inches

Step-by-step explanation:

The outside diameter is (3 1/2 ft)(12 in/ft) = 42 inches. So, its radius is 21 inches.

The inside diameter is 2 ft 10 in = 34 inches. So, its radius is 17 inches.

The difference in areas of a circle with 21 inch radius and a circle with 17 inch radius will be found using the area formula for a circle:

  A = πr²

The area difference is ...

  rim area = π((21 in)² -(17 in)²) = 152π in²

  rim area ≈ 477.52 in²

Comment on the calculation

To have an answer accurate to 5 significant digits, you must use a value for pi that is accurate to at least 5 significant digits: 3.1416 or 3.14159.

if a = 1,   and b = 2, then the answer is 47.99999999. if you round that to the nearest whole number, the answer is 48.