Three friends Adam, Betty, and Christian took turn driving cross country from Sacramento, California to Philadelphia, Pennsylvannia. Each drove for the exact amount of time, but at different average speed due to the varying landscapes. Adam drove at an average speed of 55 miles per hour through the tricky Sierra mountain range. Betty took the second leg through the relatively straight-forward (and boring) part of the trip, at an average speed of 85 miles per hour. Christian ran into some urban traffic and only managed a speed of 70 miles per hour. Together, they covered 2800 miles. What was their total driving time of the whole trip, in hours?

Potatobird Jan 24, 2021

#1**+2 **

Three friends Adam, Betty, and Christian took turn driving cross country from Sacramento, California to Philadelphia, Pennsylvannia. Each drove for the exact amount of time, but at different average speed due to the varying landscapes. Adam drove at an average speed of 55 miles per hour through the tricky Sierra mountain range. Betty took the second leg through the relatively straight-forward (and boring) part of the trip, at an average speed of 85 miles per hour. Christian ran into some urban traffic and only managed a speed of 70 miles per hour. Together, they covered 2800 miles. What was their total driving time of the whole trip, in hours?

Let the time each drove = T

So rate * time = distance.....so....

55T + 85T + 70 T = 2800

210T = 2800

T =2800/210 = 40/3 hrs each

So.....the whole trip took 3 (40/3) = 40 hrs

CPhill Jan 24, 2021