You normally drive on the freeway between San Diego and Los Angeles at an average speed of 105km/h, and the trip takes 2h and 20min . On a Friday afternoon, however, heavy traffic slows you down and you drive the same distance at an average speed of only 72.5km/h. How much longer does the trip take?
I solve for distance and get 231 km, and then set up speed=d/t, solving for t=3.19 or 199 min. I then convert 2.2h to 140min. Then I find the difference to be 59min, right? It's an online homework and it says the answer is wrong (but close!) I tried 160, too. Am I doing something wrong?
I solve for distance and get 231 km, and then set up speed=d/t, solving for t=3.19 or 199 min. I then convert 2.2h to 140min. Then I find the difference to be 59min, right? It's an online homework and it says the answer is wrong (but close!) I tried 160, too. Am I doing something wrong?
-
Let's check your numbers.
Average speed = 105 km/h, time of travel = 2h 20min = 2.3333 hr => distance = 245 km
time at slower speed = 245/72.5 = 3.379 hr = 3 hr 23 min = 203 min
The difference in time is 1 hr 3 min = 63 min
Average speed = 105 km/h, time of travel = 2h 20min = 2.3333 hr => distance = 245 km
time at slower speed = 245/72.5 = 3.379 hr = 3 hr 23 min = 203 min
The difference in time is 1 hr 3 min = 63 min