Consider Figure 2.12, for whic

Consider Figure 2.12, for which there is an institutional network connected to the Internet. Suppose that the average object size is 900,000 bits and that the average request rate from the institution's browsers to the origin servers is 15 requests per second. Also suppose that the amount of time it takes from when the router on the Internet side of the access link forwards an HTTP request until it receives the response is two seconds on average(see Section 2.2.5). (that is, the delay from Internet router to institution router)and the average Internet delay.For the average access delay,use /(1-),where  is the average time required to send an object over the access link and  is the arrival rate of objects to the access link.
a. Find the total average response time.
b. Now suppose a cache is installed in the institutional LAN. Suppose the hit rate is 0.4. Find the total response time.