Answer:
The hikers average speed due north is 0.2 km per minute.
Step-by-step explanation:
Speed is the ratio of distance moved by a body to the time taken.
i.e speed =

Since the hiker walks due north and due west, then his average speed due north can be determined by;
Average speed =

Total distance due north = 5.0 + 7.0
= 12.0 km
Total time taken = 20 + 40
= 60 minutes
= 1 hour
Average speed due north=

=

= 0.2
Average speed due north = 0.2 km/minute
The hikers average speed due north is 0.2 km per minute.