$1\mathrm{.}2$ Files can be downloaded using a broadband connection at a rate of $50{10}^6$ bits per second $(50Mbps).$ Using a fiber$-$optic cable, the download speed increases to $2$ Gbps$.$

a$)$ The pdf files for this text total about $65\mathrm{.}5{10}^6$ bytes $(65\mathrm{.}5MB).$ There are $8$ bits in a byte. How long does it take to download these files using a broadband connection?

b$)$ How long does it take to download the files from part $($a$)$ using a fiber$-$optic cable?

c$)$ The Library of Congress digital collection totals about $74$ TB$.$ How long does it take to download these files using a broadband connection?

d$)$ How long does it take to download the files from part $($c$)$ using a fiber$-$optic cable?