Use the following information to answer the given question:
\(\begin{array}{c|c} & N \\ \hline \text{Stock at 1st Jan. 1901} & 6,500 \\ \text{Stock at 31st Dec. 1901} & 5,500 \\ \text{Creditors at 1st Jan. 1901} & 4,000 \\ \text{Creditors at 31st December 1901} & 5,000 \\ \text{cash paid for goods during the year} & 20,000 \\ \text{Gross profit} & \text{25% on cost} \\ \text{Administrative and selling expenses} & 2,750
\end{array}\)
Calculate the percentage of net profit on sales