Given:
Predicted value of rain = 28 mm
Actual amount of rain = 35 mm
To find:
The percent error.
Solution:
We know that,
[tex]\text{Percent error}=\dfrac{\text{Predicted value - Actual value}}{\text{Actual value}}\times 100[/tex]
On substituting the values, we get
[tex]\text{Percent error}=\dfrac{28-35}{35}\times 100[/tex]
[tex]\text{Percent error}=\dfrac{-7}{35}\times 100[/tex]
[tex]\text{Percent error}=\dfrac{-1}{5}\times 100[/tex]
[tex]\text{Percent error}=-20\%[/tex]
Therefore, the percent error is -20%.