Question 4 (a) Solve the differential equation ey day 2 In x = (7% ) dx X (b) The rate of water loss from certain plant cell can be modeled as : dv = -kV3 k is a constant dt where I' is the amount of water in the cell in mm', and / is time in hours. It is known that the initial volume of water in a cell is 8 mm , and it drops to 1 mm after 6 hours. Find : (i) V in terms of f; (5%) (ii) Find the value of the constant k; (3%) (iii) the time when all of the water left the plant cell. (3%)