Drama, Film, and Mass Communication homework help

(f) Consider the network shown in figure 1. The hosts in the left network are requesting resources using HTTP from the origin servers on the Internet. 30% of web requests result in a cache hit (the request has been previously downloaded and can be served from the cache). Each host (not including the cache) generates a request every 20 seconds and each request requires the download of 1Mbit. What download bandwidth is needed on the access link, L1, in order for this HTTP download traffic to utilise a no more than 80% of the link download capacity?