Web Caching / Networking / HTTP

Hi I have the following question can any solve this problem

A campus network uses a single 100 Mbs LAN with average LAN delay of 10 ms. The campus is connected through a 1 Mb/s access link to the Internet. The Internet experiences an average delay time of 200 ms, while the delay (in seconds) on the access link is a function of its utilization as below:

D = 10U/1 − U

where D is the delay experienced over the access link, and U is the utilization indicating the fraction of bandwidth used on the access link (U ranges from 0 to 1). Requests are generated on the LAN with an average request size of 50 Kb (50 kilo bit) and a request frequency of 19 requests per second.

(a) Find the average end-to-end delay to service a request, when no web caching is used.

(b) What is the average end-to-end delay when a web cache is used at campus with a hit ratio of 70%?

(c) What is the average end-to-end delay when a web cache is used at campus with a hit ratio of 30%?