Question

a man cycles from A to B a distance of 21 km in 1 hour 40 minutes the road from A is level for  13 km and then it  is uphill to B. the man's average speed on level is 15k'/hr find his average uphill speed?

Answer 1

Distance travelled on level road = 13km
Average Speed on level road = 15 km/hr
Time travelled on level road = Distance/Av. Speed
                                              = 13km / 15(km/hr)
                                              = 0.87 hours = 52 mins

Distance travelled uphill = 8km (21km-13km)
Time travelled uphill = 1 hour 40 mins - 52 mins = 48 mins
Average Speed uphill =  Distance travelled / Time taken
                                     8km / (48/60 hrs) = 10 km/hr