. If you are performing a full backup each Friday to a single tape and a differential backup to a single tape on all other days of the week (including the weekend), what is the minimum number of tapes required to accommodate seven days worth of backups?

a. 2 b. 7 c. 8 d. 9

when you are backing up with a new tape on friday, you need besides the tape you are backing up to, all of last weeks seven tapes, so 8 seems to be the number.