independent variable linear equation

Question

~~3)  Given a one independent variable linear equation that states cost in $K, and given the following information, calculate the standard error and determine its meaning.

[Image Description: n =12, Summation of (Y– Yhat)2 = 10591, Ybar=314.375]
  
 
L7_e2q5.jpg
 
   If we used this equation, we could typically expect to be off by ± 32.54%.
 
   If we used this equation, we could typically expect to be off by ± $36.39K.
 
   If we used this equation, we could typically expect to be off by ± 36.39%.
 
   If we used this equation, we could typically expect to be off by ± $32.54K.

Answer 1

I don't have the image, but I guess ∑(Y-Yhat)^2=10591 is the variance and the standard error=√(10591/12) where 12 is the number of observations, n. SE=29.7083 approx. Since Y is measured in $K, SE=$K29.71 (approx) and the values are expected to be between 314.375-29.708=$K284.667 and 314.375+29.708=$K344.083.

The given figure only gives the variance between the fitted and observed values, rather than the variance between the fitted values and the mean, and there is no linear regression equation provided. Are we to assume an equation from another question you've recently submitted?

Y-Yhat=Y-Ybar-(Yhat-Ybar); 10591=∑(Y-Yhat)^2=∑(Y-Ybar-(Yhat-Ybar))^2 "="

∑(Y-Ybar)^2+∑(Yhat-Ybar)^2-2∑(Y-Ybar)(Yhat-Ybar).

We don't seem to have enough info to calculate ∑(Yhat-Ybar)^2.