posted by Shanda .
A storm is approaching from the SW at 30 mph and is 7.5 miles away. An officer is 5 miles from the storm and needs to arrive 5 minutes ahead of the storm. How fast does he need to drive to reach the storm 5 minutes ahead?
figure out how much time it takes for the storm to arrive. Subtract five minutes. Now you have the time for the officer to travel, and you know his distance, so figure speed.
time taken for the storm to arrive = 7.5/30 hrs = .25 hrs = 15 minutes
So the officer must do his 5 miles in 10 minutes to arrive 5 min ahead of the storm
speed = dist./time = 5/(10/60) = 30 mph