Radio signals travel at a rate of 3 × 108 meters per second. how many seconds will it take for a radio signal to travel from a satellite to the surface of the earth if the satellite is orbiting at a height of 7.5 × 106 meters?

The time taken for radio signal to the earth's surface we shall proceed as follows;
time=(distance)/(speed)
Distance=7.5×10^6 meters
speed=3×10^8 meters/second
therefore:
Time=(7.5×10^6)/(3×10^8)=0.025 seconds
We conclude that it will take the signal 0.025 seconds to reach the surface of the earth.