The coefficients of the regression βX|y and βY|x, are known, The coefficient of correlation equals:
1. \(\dfrac{1}{\beta_{X|y}\beta_{Y|x}}\)
2. \(\pm\sqrt{{\beta_{X|y}\beta_{Y|x}}}\)
3. \(\dfrac{2}{\dfrac{1}{\beta_{X|y}}+\dfrac{1}\beta_{Y|x}{}}\)
4. \(\dfrac{\beta_{X|y}+\beta_{Y|x}}{2}\)