Question

A person travels by car from one city to another. She drives for 20.9 min at 68 km/h, 9.82 min at 90.3 km/h, 53.4 min at 43.5 km/h, and spends 18.3 min along the way eating lunch and buying gas. DETERMINE THE AVERAGE SPEED FOR THIS TRIP. Answer in units of km/h

Answer 1

Average speed= total distance covered/total time taken

now 20.9min= .3483hr

9.82min=.1636hr

53.4min=.89hr

18.3min= .305hr

for 20.9min (.3483hr) she goes = 68* .3483= 23.6844km

for 9.82min (.1636 hr) she goes= 90.3* .1636 = 14.77308Km

for 53.4min (.89hr) she goes = 43.5 * .89 =38.715Km

Therefore total distance covered= 23.6844 + 14.77308 + 38.715 Km = 77.17248km

total time covered = .3483hr + .1636 hr + .89hr + .305hr = 1.7069hr

Average speed = 77.17248km/ 1.7069hr = 45.2120687km/hr