Convert 0.3 miles per minute to miles per hour. Round to the nearest tenth if necessary. Use $60 \mathrm{~min}=1 \mathrm{hr}$.

Step 1 ：We are given the speed in miles per minute as 0.3 and we need to convert this to miles per hour. We know that there are 60 minutes in an hour.

Step 2 ：Using this information, we can multiply the given speed by 60 to get the speed in miles per hour.

Step 3 ：\(speed_{miles\_per\_minute} = 0.3\)

Step 4 ：\(speed_{miles\_per\_hour} = speed_{miles\_per\_minute} \times 60\)

Step 5 ：\(speed_{miles\_per\_hour} = 0.3 \times 60 = 18.0\)

Step 6 ：Final Answer: The speed in miles per hour is \(\boxed{18.0}\)