Answer:
Part A) 
Part B) 
Step-by-step explanation:
Part A)
we have the formula of the volume of a cylinder

Solve for h
That means ----> isolate the variable h
Divide both side by πr²

Simplify

Rewrite

Part B) Find the height of a cylinder with a volume of 36π cm3 and a base with a radius of 3 cm
we have


substitute in the formula and solve for h


I think you would multiply 20 × 4 and the answer would be 80 that the scientist counted the number of plants in each 4 sections after 20 days.