Answer:
The answer is C.
Step-by-step explanation:
Multiply 4 by 76, 77, and 78.
4 * 76 = 304
4 * 77 = 308
4 * 78 = 312
304 = 304, so C is the correct answer.
Hope this helps!
Answer:
The rate of change in surface area when r = 20 cm is 20,106.19 cm²/min.
Step-by-step explanation:
The area of a sphere is given by the following formula:

In which A is the area, measured in cm², and r is the radius, measured in cm.
Assume that the radius r of a sphere is expanding at a rate of 40 cm/min.
This means that 
Determine the rate of change in surface area when r = 20 cm.
This is
when
. So

Applying implicit differentiation.
We have two variables, A and r, so:



The rate of change in surface area when r = 20 cm is 20,106.19 cm²/min.