Answer: Option B.
Step-by-step explanation:
If a varies directly with b then when a increases b it also increases by a factor k.
Then we can write that
We know that when a = 28 then b = 7. So
Therefore the equation of proportionality is:
So when 
then:
36/19
=1.894736842 and it keeps going
Hope this helped and have a great day!
Dr /dt = 7
A = pi r^2
dA / dr = 2pir
dA/dt = dA/dr * dr/dt = 2pir * 7 = 14pir
when r = 12 rate of change of the area = 14*pi*12 = 168pi
= 527.79 cm^2 / minute to nearest hundredth
