For the data on price (in rupees) and demand (in tonnes) for a commodity, calculate the co-efficient of correlations.

Price(X)	22	24	26	28	30	3	34	36	38	40
Demand(Y)	60	58	58	50	48	48	48	42	36	32

Obtain the two regression lines from the following

X	6	2	10	4	8
Y	9	11	5	8	7

With the help of the regression equation for the data below, calculate the value of X when Y=20

X	10	12	13	17	18
Y	5	6	7	9	13

A computer while calculating the correlation co-efficient between two variables x and y from 25 pairs of observations, obtained the following results. \(\sum\)x=125, \(\sum\)x²=650, \(\sum\)y=100, \(\sum\)y²=460, xy=508. It was later found out that it had copied down two pairs as while the correct values are 

x	y
6	14
8	6

 

x	y
8	12
6	8

Obtain the correlation co-efficient for the correct value.

The equations of two regression lines are 4x+3y+7=0 and 3x+4y+8=0.
Find (i) the mean of x and the mean of y
(ii) the regression co-efficient b_xy and b_yx 
(iii) the correlation co-efficient between x and y.