Picnickers see a lightning flash and hear the resulting thunder 9.0 s later. If the storm is traveling at a
rate of 15 km/h, then how long, in minutes, do the picnickers have before the storm arrives at their
location?
According to Wikipedia the speed of sound is about 343 m/s in air.
343 m/s x 9 s = 3087 meters = 3.087 km
15 km/hr x # hr = 3.087
# hr = 3.087/15 = 0.206 hr or
0.206 hr x 60 min/hr = about 12 min.
Check my thinking and my work.