Question

Sally travels by car from one city to another. She drives for 26.0 min at 56.0 km/h, 41.0 min at 31.0 km/h , and 14.0 min at 85.0 km/h, and spends 15.0 min eating lunch and buying gas.

(a) Determine the average speed for the trip
(b) Determine the total distance traveled

Answer 1

First distance:

Distance(d) = speed(s) * time(t)

=56 * 26/60 = 24.3km (to one decimal place)

Second distance:

d = s * t

= 31 * 41/60 = 21.2km (to one decimal place)

Third distance:

d = s * t

= 85 * 14/60 = 19.8km (to one decimal place)

Average speed:

Average speed = (distance)/(total time)

distance = 24.3 + 21.2 + 19.8 = 65.3km (to one decimal point)

total time = (26 + 41 + 14 + 15)/60 hrs = 96/60 = 1.6hrs

Average speed = 65.3km / 1.6hrs = 40.8km/hr (to one decimal point)

Total distance:

Total distance = average speed times time spent travelling

= 40.8 * 81/60 = 55.1km (to one decimal point)