Final answer:
The percent error for the thermometer when measuring a child's temperature of 97.8 degrees F as 98.1 degrees F is approximately 0.31%.
Step-by-step explanation:
To calculate the percent error of the thermometer in measuring a child's temperature, we will use the formula:
Percent Error = (|Actual Value - Measured Value| / Actual Value) × 100%
In this case, the actual temperature of the child is 97.8 degrees F, while the measured temperature is 98.1 degrees F.
Plugging in the values we get:
Percent Error = (|97.8 - 98.1| / 97.8) × 100%
Percent Error = (0.3 / 97.8) × 100%
Percent Error ≈ 0.307 × 100%
Percent Error ≈ 0.31%
The thermometer's percent error is approximately 0.31%.