How fast will they have to drive ?

Question

Lou leaves fra cross country excursion traveling on a bicycle at 30 miles per hour. His friends are driving the trip and will meet him at serveral rest stops along the way. The first stop is scheduled 20 miles from the original starting point. If the people driving leavve 15 minutes after Lou from the same place, how fast will they have to drive to reach the frist rest stop at the same time as Lou ?

Answer 1

(30 miles/hr) * t = 20 miles

t = 20 / 30 = 2/3 hours

(2/3 hours - 1/4 hours) * v_car = 20 miles

(8/12 hours - 3/12 hours)* v_car = 20 miles

5/12 hours * v _car = 20 miles

12/5* (5/12 hours) * v_car = (20 miles)*(12/5)

v_car = (240/5 miles per hour) or 48 miles per hour.