use the for loop and if statement to solve it?

Question 1: Suppose a reactor normally contains 12 units of dissolved oxygen in a fixed volume of water. Suppose at t = 0 minute a quantity of organic waste is introduced, then the oxygen concentration in the reactor can be described by 2t2 - 15t 12 t2 +1 a) Write a method that returns the time, tmin, at which concentration is minimum. b) Write a method that returns the concentration at tmin c) Write a method that returns the time when the concentration returns back to X units, where X is the user input and satisfies 0X 3 12. Return the time in hours. Use IC(t)-