A person travels by car from one city to another with different constant speeds between pairs of cities. She drives for 40.0 min at 85.0 km/h, 12.0 min at 95 km/h, and 35.0 min at 30.0 km/h, and spends 35.0 min eating lunch and buying gas. Determine the average speed for the trip?
Use the same method as this question's answer. The numbers are different.
http://www.jiskha.com/display.cgi?id=1254706350
Add the non-driving time to the driving time and convert to hours. Then divide the total distance by that total time in hours.
time
34.9+12.8+50.4+18.8=116.9/60=19.483hrs
distance
76.5+96.7+37.7=210.9
210.9km/1.1083hrs=190.2914km/h ??????
done it so many times am so confuse!!!
Why are you using 1.1083 hr for total time? You already computed 19.483 hr, which should have been 1.9483 hr.
To determine the average speed for the trip, we need to find the total distance traveled and divide it by the total time taken.
First, let's calculate the distances traveled during each leg of the journey:
Distance1 = Speed1 * Time1
Distance1 = 85.0 km/h * (40.0 min / 60.0 min/h) = 56.67 km
Distance2 = Speed2 * Time2
Distance2 = 95 km/h * (12.0 min / 60.0 min/h) = 19.0 km
Distance3 = Speed3 * Time3
Distance3 = 30.0 km/h * (35.0 min / 60.0 min/h) = 17.5 km
Now let's find the total distance traveled:
Total Distance = Distance1 + Distance2 + Distance3
Total Distance = 56.67 km + 19.0 km + 17.5 km = 93.17 km
Next, we need to find the total time taken:
Total Time = Time1 + Time2 + Time3 + Time4 (lunch and gas time)
Total Time = 40.0 min + 12.0 min + 35.0 min + 35.0 min = 122.0 min
Now, we can calculate the average speed:
Average Speed = Total Distance / Total Time
Average Speed = 93.17 km / (122.0 min / 60.0 min/h) = 45.84 km/h
Therefore, the average speed for the trip is approximately 45.84 km/h.