Answer:
4. 4.66hours
5. time_trip = 2.777 h
Step-by-step explanation:
4. A jet plane travels 2 times the speed of a commercial airplane. The distance between Vancouver and Regina is 1730 km. If the flight from Vancouver to Regina on a commercial airplane takes 140 minutes longer than a jet plane, what is the time of a commercial plane ride of this route?
We know that
Speed_commercial = distance/ time_comm
Speed_commercial = 1730 km/ time_comm
Then,
Speed_jet = distance/ time_jet = 2*Speed_commercial
Speed_jet = 1730 km/ time_jet = 2*Speed_commercial
time_comm = 2.333 h + time_jet
1730 km/ time_jet = 2*1730 km/ time_comm
time_comm = 2*time_jet
time_comm = 2*(time_comm - 2.333h)
time_comm = (2*time_comm - 4.666h)
time_comm = 4.666 h
5. A man goes fishing in a river and wants to know how long it will take him to get 10km upstream to his favourite fishing location. The speed of the current is 3 km/hr and it takes his boat twice as long to go 3km upstream as is does to go 4km downstream. How long will it take his boat to get to his fishing spot?
Distance = 10 km upstream
Speed_current = 3 km/h
Upstream
(Speed_boat - Speed_current) = 3 km / (2*time_downstream)
Downstream
(Speed_boat + Speed_current) = 4 km / (time_downstream)
We subtract both equations
(Speed_boat + Speed_current) - (Speed_boat - Speed_current) = 4 km / (time_downstream) - 3 km / (2*time_downstream)
2*Speed_current = (5/2 km)/ time_downstream
2*(3 km/h)= (5/2 km)/ time_downstream
time_downstream = 0.416 h
(Speed_boat + 3km/h) = 4 km / (0.416 h)
Speed_boat = 6.6 km/h
Trip upstream
(Speed_boat - Speed_current) = 10 km / (time_trip)
time_trip = 10 km/(3.6 km/h) = 2.777 h
time_trip = 2.777 h
