Determine first the difference between the incorrectly measured board and the correct one. The subtraction would result to 1.2 ft. The percent error is calculated by dividing this value by the correct value and then multiply by 100%. (1.2 ft / 12 ft) x 100% = 100%. Thus, the percent error is 10%.
The distance from the top car to the bottom car is equal to the diameter of the wheel. The diameter is 40 m, and that is twice the radius. The radius of the Ferris wheel is (40 m)/2 = 20 m.
