Assign ranks to the marks in Accountancy (X) and Marks in Statistics (Y).

The formula for Spearman's rank correlation coefficient ($\rho$) is:

$$\rho = 1 - \frac{6 \sum d^2}{n(n^2 - 1)}$$

where $n$ is the number of pairs of observations. In this case, $n=5$.

Substitute the values into the formula:

$$\rho = 1 - \frac{6 \times 10}{5(5^2 - 1)}$$ $$\rho = 1 - \frac{60}{5(25 - 1)}$$ $$\rho = 1 - \frac{60}{5(24)}$$ $$\rho = 1 - \frac{60}{120}$$ $$\rho = 1 - 0.5$$ $$\rho = 0.5$$

The Spearman's rank correlation coefficient is 0.5.