Bunuel
Mike and Fritz ran a 30-mile Marathon. Mike ran 10 miles at 10 miles per hour and then ran at 5 miles per hour for the remaining 20 miles.Fritz ran the first one-third (by time) of the run at 10 miles per hour and the remaining two-thirds of the run at 5 miles per hour. How much time in hours did Fritz take to complete the Marathon?
(A) 3
(B) 3.5
(C) 4
(D) 4.5
(E) 5
Solution:
Let t be the total amount of time it took Fritz to complete the Marathon. Then, Fritz ran for t/3 hours at 10 mph and 2t/3 hours at 5 mph. Since distance = rate x time, Frits ran a total of 10 * t/3 + 5 * 2t/3 = 10t/3 + 10t/3 = 20t/3 miles. We are told that the total distance is 30 miles, so let’s set the expression 20t/3 equal to 30:
20t/3 = 30
2t = 9
t = 4.5 hours
Notice that since we already know the total distance is 30 miles, the given information about Mike is completely unnecessary.
Answer: D