Answer:
Percent error is calculated using the formula:
Percent Error = ( |Predicted Value - Actual Value| / Actual Value ) * 100%
Plugging in Brianna's prediction and the actual number of puppies sold:
Percent Error = ( |16 - 9| / 9 ) * 100%
The absolute value of (16 - 9) is 7, so the calculation becomes:
Percent Error = ( 7 / 9 ) * 100%
This is approximately 77.78%, which is Brianna's percent error in her prediction.