c) The time spent (in minutes) on renewing driving license at the counter can be modelled by the continuous random variable with probability density function given by f(x) = [hx 25 x21, 0 otherwise, where h is a constant. (i) Calculate the value of h. (3 marks) (ii) Calculate the mean time spent on renewing driving license. (3 marks) (iii) Calculate the probability that a person chosen at random spent between 2 and 5 minutes at the counter