6.4 An accounting firm that does not have its own computing facilities rents time from a consulting company.

The firm must plan its computing budget carefully and hence has studied the weekly use of CPU time quite thoroughly.The weekly use of CPU time approximately follows the probability density function given below (measurements in hours):

a Find the distribution function F(x) for weekly CPU time X.

b Find the probability that CPU time used by the firm will exceed 2 hours for a selected week.

c The current budget of the firm covers only 3 hours of CPU time per week. How often will the budgeted figure be exceeded?

d How much CPU time should be budgeted per week if this figure is to be exceeded with probability only 0.10?