Answer: 11.43%
Explanation:
The above question will be calculated using:
Percent error = (Estimated value-Actual value) / Actual value × 100
where,
Estimated value = 3.9cm
Actual value = 3.5cm
Percentage error= (3.9 - 3.5) / 3.5 × 100
= (0.4 / 3.5) × 100
=11.43%
Alex percent error is 11.43%.