Before contracting to grind engine cylinders to a cross-sectional area of 9 in², you need to know how much deviation from the ideal cylinder diameter of c = 3.385 in. you can allow and still have the area come within 0.01 in² of the required 9 in². To find out, you let A = π(x/2)² and look for the interval in which you must hold x to make |A - 9| ≤ 0.01. What interval do you find?