Answer:
- plane: 850 mph
- jet stream: 150 mph
Step-by-step explanation:
The speed of the plane is the average of the two speeds. The speed of the jet stream is half their difference.
against: (5600 mi)/(8 h) = 700 mi/h
with: (4000 mi)/(4 h) = 1000 mi/h
Plane's speed = (700 + 1000)/2 mi/h = 850 mi/h
jetstream speed = (1000 -700)/2 mi/h = 150 mi/h
The rate of the jet in still air is 850 mi/h; the rate of the jetstream is 150 mi/h.
