Let us find the average of 3 fractions:

1/2 1/3 and 1/4

In general to find the average of 3 fractions (or non fractions) you add the fractions together and divide by 3 (or however many fractions you have.

In this case:

(1/2 + 1/3 + 1/4)/3 ; least common denominator for the fractions is 12 rewritten:

(6/12 + 4/12 + 3/12)/3

(13/12)/3

or

(13/36)