If the regression coefficient of x on y and y on x are $$ - {1 \over 2}$$ and $$ - {1 \over 8}$$, respectively then what is the correlation coefficient between x and y?

A sample of 5 observations has mean 32 and median 33. Later it is found that an observation was recorded incorrectly as 40 instead of 35. If we correct the data, then which one of the following is correct?

The correlation coefficient computed from a set of 30 observations is 0.8. Then, the percentage of variation not explained by linear regression is

The average age of a combined group of mean and women is 25 yr. If the average age of the group of men is 26 yr. and that of the group of women is 21 yr, then the percentage of men and women in the group is respectively