(a) Database transactions perform an average of 4.5 disk operations on a database server with a single disk. The database server was monitored during one hour and during this period, 7,200 transactions were executed. What is the throughput of the disk (in transactions per second)? If each disk operation takes 20msec on average, what is the disk utilization? (b) What is the average processing time (per operation) for the disk in (a)? (c) A corporate portal provides Web services to the company's employees. On average, 500 employees are online requesting Web services from the portal. An analysis of the portal's log reveals that 6,480 requests are processed per hour on average. The average response time was measured as 5 seconds. What is the average think time of an employee