In the race Math 600, drivers must complete 200 laps of 3 miles each. Dave drove the first 150 laps at 180 mph and the last 50 laps at 200 mph. What was Dave's average speed for the race, in miles per hour? Express your answer as a common fraction.

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HIHIBIGBRAIn Oct 31, 2019

edited by
Guest
Oct 31, 2019

edited by Guest Oct 31, 2019

edited by Guest Oct 31, 2019

edited by Guest Oct 31, 2019

edited by Guest Oct 31, 2019

edited by Guest Oct 31, 2019

edited by Guest Oct 31, 2019

#1**+2 **

These type of questions appear fairly regularly on the forum..... they are a little tricky....you must remmeber to take into acount TIME not just distance and speed.

Rate x time = distance

distance /rate = time

((150 laps x 3 mi/lap )/180m/hr + (50 laps x 3 mi/lap)/200mi/hr ) = 2.5 hr + .75 hr = 3.25 hr for 600 miles

distance/time = rate 600 m / 3.25 hr = 60000/325 = 2400/13 = 184.62 m/hr

ElectricPavlov Oct 31, 2019