Answer:
Step-by-step explanation:
speed of light ≈ 300 000 000 m/s
a) How long would it take a message sent as radio waves from Earth to reach Mars when Mars is nearest Earth?
(230e9 - 150e9) / 3e8 = 277 s or 4 minutes 27 seconds.
b) How long would it take a message sent as radio waves from Earth to reach Mars when Mars is farthest from Earth?
(230e9 + 150e9) / 3e8 = 1267 s or 21 minutes 6 seconds.