If regression lines are 8x – 10y + 66 = 0 and 40x – 18y = 214 then correlation coefficient between x & y is a) -1 b) 0.6 c) -0.6 d) 1

the regression equations are y = 08x+6.6 and x = 0.45y+5.35 so byx = 0.8 and bxy=0.45 so r = g.m of bxy and byx = root(0.8*0.45)=0.6

I have one all the more quick trap of settling this question. 1)If we assume first condition to be Y on X then just move the co-effective of Y as denominator and move the co-productive of X as numerator by changing the sign. This division acquired is our Byx. Additionally rehash a similar procedure for Bxy. 2)Now look at that is it approving for connection coefficient? If not then switch the procedure by accepting first condition to be X on Y. 3)And then apply the recipe.