How long does it take the signal from a local radio station
totravel 20 miles?

Time,

Explanation:

It is given that,

Distance traveled by the signal from a local radio station, d = 20 miles

1 mile = 1609.34 m

Distance, d = 32186.9 m

Speed of the radio signal,

Let t is the time taken by the signal from a local radio station  to travel 20 miles. The speed is given by :

So, the time taken by the signal from a local radio station  to travel 20 miles is . Hence, this is the required solution.

the independent variable, the one that is intentionally manipulated, is whether or not the car hits the barrier.

the dependent variable, the one that you measure the response in, is the distance that the washers travel.