If the correlation coefficient between x and y is 0.6, covariance is 27 and variance of y is 25, then what is the variance of x?

Let $$\overline x $$ be the mean of x₁, x₂, x₃, ....., x_n. If x_i = a + cy_i for some constants a and c, then what will be the mean of y₁, y₂, y₃, ....., y_n ?

Consider the following statements

I. If the correlation coefficient r_xy = 0, then the two lines of regression are parallel to each other.

II. If the correlation coefficient r_xy = 1, then the two lines of regression are perpendicular to each other.

Which of the above statements is/are correct?

If 4x $$-$$ 5y + 33 = 0 and 20x $$-$$ 9y = 107 are two lines of regression, then what are the values of $$\overline x $$ and $$\overline y $$ respectively ?