Design a backup strategy for a computer system. One option is to use plug$-$in external disks, which cost SAR$150$ for each $500$ GB drive. Another option is to buy a tape drive for SAR $5000,$ and $400$ GB tapes for SAR $50$ apiece. A typical backup strategy is to have two sets of backup media onsite, with backups alternately written on them so in case the system fails while making a backup, the previous version is still intact. There's also a third set kept offsite, with the offsite set periodically swapped with an on$-$site set.

a$.$ Assume you have $[92]$ TB $(1$ TB $=1000$ GB$)$ of data to back up$.$ How much would a disk backup system cost?

b$.$ How much would a tape backup system cost for $[92]$ TB$?$

c$.$ How large would each backup have to be in order for a tape strategy to be less expensive?

d$.$ What kind of backup strategy favors tapes?

Important: Show stepwise calculations for all parts. Highlight your answers. Failure to comply with instruction will result in marks deduction.