2:39 '6' E} gth of a telephone call made to a company is denoted by the c ' us T. It is modelled by the probability density function E f _ In 0 g rg 10 (t) _ 0 othenvise (a) Show that the value of k is i. 50 (3) (b) Find PC!" > 6). (2) (c) Calculate an exact value for EU) and for Var). (5) (d) Write down the mode of the distribution of T. (1) It is suggested that the probability density function, t). is not a good model for T. (e) Sketch the graph of a more suitable probability density function for T. (1)