Answer
6.7%
Work Step by Step
The base is the total amount of oil, 4.5 qt. The part is the amount in the filter, 0.3 qt. The percent is unknown.
$R=\frac{P}{B}=\frac{0.3}{4.5}=0.0666\overline6$
To convert the rate to a percent, move the decimal two places to the right. Round to the nearest tenth.
$0.0666\overline6\approx6.7\%$
