Option A 2012

[Dreyfus]

I hv a doubt in the question , acc to it the beta should be 0 therefore X=X bar and Y=Y bar but how it is determine whether they intersect at 90° or not?

[Akshay Jain]

take X-Y plane with observations (x,y) such that the correlatiob coefficient is 0 between them...
if u take linear regression Y=f(X) then the slope coefficient will come out to be 0 because of 0 correlation, there will be only intercept term Y= some constant (this will be parallel to X axis)
now if u take linear regression X=f(Y) then the slope coefficient will come out to be 0 because of 0 correlation, there will be only intercept term X= some constant (this will be parallel to Y axis)

Two lines, one is parallel to X axis and other is parallel to y axis are perpendicular to each other

[Dreyfus]

Thankx Akshay.......i used the formulae for angle b/ w two lines using slopes nd it really worked well.....but ur reasoning is more efficient.....