Step 1: Set up comparable lots.
Let the cost price be ₹ $C$ per dozen.
Then CP per $100$ apples $=\dfrac{100}{12}\,C=\dfrac{25}{3}C$.
Step 2: Interpret the selling condition.
"Sells at eight times per hundred'' \Rightarrow\ selling price per $100$ apples $=8C$.
Step 3: Compute gain/loss percent on a $100$-apple lot.
Profit (or loss) $= \text{SP}-\text{CP}=8C-\dfrac{25}{3}C=\left(8-\dfrac{25}{3}\right)C=-\dfrac{1}{3}C$.
Loss percent $=\dfrac{\text{Loss}}{\text{CP}}\times 100
=\dfrac{\frac{1}{3}C}{\frac{25}{3}C}\times 100=\dfrac{1}{25}\times 100=4\%$.
\[
\boxed{\text{Loss }=4\%}
\]