(a) The regression equation is Y' = 4.42 + 1.38(9) = 17.14
(b) When X is 9, then Y' = 17.14.
To find the regression equation and the value of Y' when X is 9, we can use the given sample observations and perform a linear regression. The regression equation for a simple linear regression is of the form Y' = a + bX, where Y' is the predicted value of Y, a is the intercept, b is the slope, and X is the independent variable.
Using the given sample observations, we can perform a linear regression to find the values of a and b, and then use the regression equation to find the predicted value of Y when X is 9.
The regression equation for the given sample observations is Y' = 4.42 + 1.38X. Therefore, when X is 9, the predicted value of Y is:
Y' = 4.42 + 1.38(9) = 17.14
So, when X is 9, the predicted value of Y is 17.14.