To find the total length of all 4 pieces, you will use the line plot to list the lengths and then add then together.
6 1/4 + 6 1/2 + 6 5/8 + 7; create equivalent fractions with common denominators.
6 2/8 + 6 4/8 + 6 5/8 + 7 = 25 11/8
25 + 11/8 (1 3/8) = 26 3/8 inches.
The 4 pieces were 26 3/8 inches long.