The questions are in the image below

If f (x) = 3x4 4x3, Find the critical points and the interval where f(x) is decreasing. \fIf the volume of a spherical organism is increasing at a rate of 4.8xcm2/ week, then at what rate is the radius increasing when the radius is 2cm. During the course of an epidemic, assume that the number N (I) of the people infected at a timer is given by : N6) = 300:4'3e'("3) , where I is measured in weeks from the start of the epidemic. At what rate is the number of people infected changing at time I = 8 weeks The distance of a bead moving on a straight wire from a fixed point on a wire at a time t is: S(t) = tsin(t) Then find the acceleration A (t ) at time t. What is the acceleration at t=3s