Consider the following scenario: access link rate: $1\mathrm{.}54$Mbps$,$ RTT from institutional router to server: $1$ sec$,$ web object size: $100$k bits, average request rate from browsers to original servers: $12$ objects$/$sec$.$ For access link, assume link delay is $5$ minutes when utilization over $90\%,4$ minutes when utilization between $60\%-90\%,1$ minute when between $40\%-60\%$ and $10$ seconds when utilization below $40\%.$ Assume the delay is constant: $2$ seconds.

A$)$ What's the end$-$end delay if there is no web cache?

B$)$ What's the end$-$end delay if there is a web cache, suppose cache hit rate is $0\mathrm{.}6.$