Jill estimated a room to be 18ft tall. It was actually only 15 ft tall. What is her percentage of error?
To find the percentage of error, we need to divide the difference between the estimated and actual values by the actual value and then multiply by 100.
The difference between the estimated and actual values is 18 ft - 15 ft = 3 ft.
The percentage of error is (3 ft / 15 ft) * 100% = 20%.
Therefore, Jill's percentage of error is 20%.