### Home > ACC7 > Chapter 8 Unit 5 > Lesson CC2: 8.1.1 > Problem8-16

8-16.

Mariana and Felix were in science class and were using a test kit to measure the amount of calcium in milk. They measured the amount of calcium in $1$ cup of milk $10$ times and got a mean of $294.6$ mg. They looked up the amount of calcium that is typically in milk and found out it was $290$mg per $1$ cup. Percent error finds the difference between the actual value and measured value and the compares that difference to the actual value as a percentage. Find the percent error of Mariana and Felix’s measurement.

Find the difference between the measured value and the actual value.
$294.6-290=4.6$

Divide the difference by the actual value.

$\frac{4.6}{290}=0.0158$

Multiply this number by $100\%$ to get the percent error.
$(0.0158)(100\%)=\ \text{about}\ 1.6\%$

About $1.6\%$