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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.

 

 

 

PLZ HELP QUICK URGENTsurprise

 

ANYBODY!!!!!

 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
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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

 Oct 31, 2019
edited by ElectricPavlov  Oct 31, 2019
 #2
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THANK YOU SO MUCH

 

 

Now I get it

 Oct 31, 2019
 #2
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THANK YOU SO MUCH

 

 

Now I get it

Guest Oct 31, 2019
 #4
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THANK YOU

 Oct 31, 2019

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