Question

Keiko estimated the height of her office building to be 45 ft. The actual height of her office building is 42 ft

Answer 1

% error formula: | true value minus "your" (as in Keiko's) value | over true value, times 100.

so: 42 - 45 = 3 (it would be negative but we used absolute value, which is how it is supposed to be done. 3 is your absolute error).

3/42 = 0.07143

0.07142 * 100 = 7.142%. she was only 7.142% off from the right answer.