A motorcyclist travels for 15 minutes at 120km/h, 1h 30mins at 90km/h and 15 minutes at 60km/h. At what speed would she have to travel to perform the same journey, in the same time, without changing speed?

1 Answer
Mar 19, 2018

90"km/h"

Explanation:

The total time taken for the motorcyclist's journey is

0.25"h" (15"min") + 1.5"h" (1"h" 30"mins") + 0.25"h" (15"min") = 2 "hours"

The total distance travelled is

0.25\times120 + 1.5\times90 + 0.25\times60 = 180"km"

Therefore the speed she would have to travel at is:
180/2 = 90"km/h"

Hope that makes sense!