The population of a certain type of berry bush in a conservation area is represented by the function p(t)=3√(16t+50t3)3p(t)=(16t+50t3)33, where pp is the number of berry bushes and tt is time, in years.

a) Determine the rate of change of the number of berry bushes after 5 years.

b) When will there be 40 berry bushes?

c) What is the rate of change of the berry bush population at the time found in part b)?