SACHITH N

CAT Preparation Community 5y ago

The radius of a spherical ballon, of 30units , increases at the rate of 2units per second. then it's curved surface area increase by? the answer is given as 480pie sq units/sec. but for spheres for r=30, CSA= 3600pie sq units. after 1sec, for r=32, CSA = 4096pie sq units. so, change in CSA = 496pie sq units/sec. why is this wrong?