Which one of the following formulae is used to calculate the standard error of coefficient of…

For the t-based test of zero population Pearson correlation, the estimated standard error is $\sqrt{\frac{1-r^{2}}{n-2}}$, with $t=r/\mathrm{SE}(r)$ and $n-2$ degrees of freedom. For 25 paired observations, the denominator within the square root is 23. The expression $(1-r^{2})/\sqrt{n}$ is the conventional large-sample approximation; multiplying it by 0.6745 gives the probable error. The reciprocal square-root expression is not the standard error.