Math
posted by boobies .
Mary is blowing up a birthday balloon.After the first breath, the balloon has a 5 cm diameter . the diameter increases at a constant rate of 20% each second. What is the diameter of the balloon after 3 seconds?

is the answer 8 cm?

after 1st breath , diameter = 5cm
after 2nd breath , diamieter = 1.2(5) =
after 3rd breath, diameter = 5(1.2)^2=
(this question is physically unrealistic, Mary would be inserting the same amount of volume, which would show up with smaller and smaller increases in the diameter, certainly not a steady 20% increase each second) 
after 1st breath , diameter = 5cm
after 2nd breath , diamieter = 1.2(5) =
after 3rd breath, diameter = 5(1.2)^2= 
The diameter of the balloon after 3 s is 8.64cm.