To find the length of the diagonal of a cube, we can use the formula for the space diagonal \( d \) of a cube, which is given by:
\[ d = a\sqrt{3} \]
where \( a \) is the length of an edge of the cube.
Given that \( a = 8 \) in, we can substitute this value into the formula:
\[ d = 8\sqrt{3} \]
Next, we can approximate \( \sqrt{3} \). The approximate value of \( \sqrt{3} \) is about \( 1.732 \).
So, we can calculate:
\[ d \approx 8 \times 1.732 \approx 13.856 \]
Now, rounding \( 13.856 \) to the nearest tenth, we get:
\[ d \approx 13.9 \text{ in.} \]
Therefore, the length of the diagonal of the cube is approximately 13.9 in.