8
Guests = 320; Portions of beets served = 8 oz; Size of beet can = 40 oz.
You would need 64 cans of beets.
320 x 8 = 2560 oz of beets needed in total
2560 / 40 = 64 cans of beets @ 40 oz per can.
Added 11/18/2015 10:12:33 AM
This answer has been confirmed as correct and helpful.