written 2.3 years ago by |
Given,
x + 6y = 6
3 x + 2 y =10
To find : -
(i) sample means $\overline x\ and\ \overline y$ = ?
(ii) Coefficient of correlation between x and y = ?
(i) Since the given equations are :-
x + 6y = 6 ..........(a)
3 x + 2 y =10 ..........(b)
Let's multiply equation (a) by 3 to cancel x from equation (b).
So, Now we have -
3x + 18y = 18
3x + 2y = 10
Now subtracting these two equations we get,
$\implies (3x + 18y) - (3x + 2y) = 18 - 10$
$\implies (16 y) = 8 $
$\implies y = \frac{1}{2}$
Now, Putting the value of y in equation (b) we get,
$\implies 3x + 2\frac{1}{2} = 10$
$\implies x = 3$
(ii) If the line $x + 6y = 6$ is the line of regression of y on x, then of regression of y on x, then
by $=-x + 6 $ i.e $y = -1/6x + 1 \space\space byx = -1$
If the line $3x + 2y = 10$ is the line of regression of x on y then
$$3x = -2y + 10\ i.e\ x = -2y/3 + 10/3$$
$Bxy = -2/3\\ r=\sqrt{byx\times bxy}=\sqrt{\dfrac {-1}6\times \dfrac {-2}3}=\sqrt{\dfrac 19}=\dfrac 13 $
Since byx and bxy are negative.
X is greater.
$$\therefore x=\dfrac {-1}3$$