The time between lightning flash and the following thunderclap may be used to estimate, in kilometers, how far away a storm is.
How far way is a storm if 9 seconds elapse between the lightning and the thunderclap? Use the formula d = t/3, where t is the time, in seconds, between the flash and the thunderclap.
a. 27 kilometers
b. 18 kilometers
c. 12 kilometers
d. 3 kilometers
(I think the answer is d but I'm unsure, please help!)