Is it possible to assign weight to a set of columns when averaging data?

[tacomcnacho]

I'm trying to average test scores but with the condition that the 5 regular tests are worth 75% of the final grade and the final exam is worth 25%. Can I assign the 5 regular exam columns to be worth 75% and the final exam column to be worth 25%?

[rcm]

take a look, is this any help?

[Crooza]

Sounds like you really want the weighted score of A1 x0.15 + B1 x 0.15 + C1 x 0.15 +D1 x 0.15 + E1 x 0.15 + F1 x 0.25