Suppose a $100-$Mbps point$-$to$-$point link is being set up between Earth and a new lunar colony. The distance from the moon to the Earth is approximately $385,000km,$ and data travel over the link at the speed of light $-3{10}^8\frac{m}{s}.$

$($a$)$ Calculate the minimum RTT for the link.

$($b$)$ Using the RTT as the delay, calculate the delay $$ bandwidth product for the link.

$($c$)$ What is the significance of the delay $x$ bandwidth product computed in $($b$)?$

$($d$)$ A camera on the lunar base takes pictures of the Earth and saves them in digital format to disk. Suppose Mission Control on Earth wishes to download the most current image, which is $25MB.$ What is the minimum amount of time that will elapse between the instant when the request for the data goes out and the transfer is finished?