Given,
The data of the length of the fishes is,
class interval frequency
2 - 5 10
6 - 9 12
10 - 13 6
14 - 17 7
Required
The mean length of the fishes.
Taking the class interval as,
class interval x frequency
1.5 - 5.5 3.5 10
5.5 - 9.5 7.5 12
9.5 - 13.5 11.5 6
13.5 - 17.5 15.5 7
Mean length of the fishes is,
[tex]\begin{gathered} Mean=\frac{3.5\times10+7.5\times12+11.5\times6+15.5\times7}{35} \\ =\frac{35+90+69+108.5}{35} \\ =\frac{302.5}{35} \\ =8.64 \end{gathered}[/tex]Hence, the mean length of the fishes is 8.64 inches approximately.