#### Answer

21.1%

#### Work Step by Step

The base is the total length of the trip, which is the sum of the amount under VFR and the amount under IFR.
$B=1.5+0.4=1.9$ hours
The part is the amount of time flown under IFR, 0.4 hours.
The rate is unknown.
$R=\frac{P}{B}=\frac{0.4}{1.9}=0.2105$
To convert the decimal to a percent, move the decimal two places to the right. Round to the nearest tenth.
$0.2105\approx21.1\%$