Answer:
The average altitude change of plane with time is 8,000 feet per min .
Explanation:
Given as :
The initial height of plane after 1 min take off = 4,000 feet
The final height of plane after 3 min later = 20,000 feet
Let The rate of change of altitude in feet per min = s feet per min
Now, According to question
The change in altitude = final altitude - initial altitude
Or, D = 20,000 feet - 4,000 feet
I.e Distance change = 16,000 feet
The change in time = final time - initial time
Or T = 3 min - 1 min
I.e Time change = 2 min
Speed =

So, s =
feet per min
∴ s = 8,000 feet per min
So, Rate of change of altitude with respect to time = s = 8,000 feet per min
Hence The average altitude change of plane with time is 8,000 feet per min . Answer