11. Air is pumped into a spherical balloon such that the surface area of the balloon increases at a rate of 10 cm² per second. Find the rate at which the radius is increasing when the radius is 4 cm. [i. e. find dr/dt when r=4] [Note : surface area, A = 4pi r2]​

Ascientist has 50 grams of a radioactive element. the amount of radioactive element remaining after t days can be determined using the equation (1) after two days the scientist receives a second shipment of 50 grams of the same element. the equation used to represent the amount of shipment 2 remaining after t days is 10) - 50 which of the following is an equivalent form of the expression for the amount remaining in shipment 2? what’s the answer?