Recent content by 321study

Ok I did it. Here is my working: 4\pir2 = 200 r2 = 200/4\pi r = Square root of 50/\pi dS/dr = 8\pir = 8\piSquare root of 50/\pi = 100.27 cm2/cm Thanks everyone for all your help :smile:

Unfortunately I won't be able to view the video as it will take a while to download and I've got to get going to school for an excursion. Thank you though. So if I try: 200*4pi = 2513.27 Get the square root of that makes 50.1325 Multiple by 2 for some reason? Makes 100.265. Rounded off...

Homework Statement I am 99% positive I did a) correctly, as the answer is correct according to the answer in the back of my textbook. However, I cannot do b). The question: A spherical balloon is being inflated. Find the rate of change of the surface area with respect to the radius when...