Answer
It takes a radio signal $~~5.0\times 10^{-4}~s~~$ to travel 150 km.
Work Step by Step
A radio signal is an electromagnetic wave, so it travels at the speed of light.
We can find the time it takes a radio signal to travel 150 km:
$t = \frac{d}{c} = \frac{150\times 10^3~m}{3.0\times 10^8~m/s} = 5.0\times 10^{-4}~s$
It takes a radio signal $~~5.0\times 10^{-4}~s~~$ to travel 150 km.
