Question

184. A student estimated a mass to be 40 g. After carefully measuring, she

found the actual mass to be 45 g. What is the percent of error?

Answer 1

`\boxed {\boxed {\sf About \ 11 \%}}`

Explanation:

The formula for percent error is:

`\% \ error = | (measured \ value - actual \ value )/(actual \ value) | *100`

For this, the measured value is the estimation of 40 grams. The actual value is the true mass of 45 grams.

`measured = 40 \ g \\actual = 45 \ g`

`\% \ error = | (40 \ g - 45 \ g )/(45 \ g ) | *100`

Solve the numerator.

• 40 grams - 45 grams = -5 grams

`\% \ error = | (-5 \ g )/(45 \ g ) | *100`

Divide.

`\% \ error = | (-5 \ g )/(45 \ g ) | *100`

`\% \ error = | -0.111111111| *100`

`\% \ error = 0.111111111*100\\\% \ error = 11.11111 \\\% \ error \approx 11`

The percent error is about 11%