Consider the Following Data That Was Fitted Using a Linear

Consider the following data that was fitted using a linear trend.
$$\begin{array} { | c | c | c | } \hline \text { Period } & \begin{array} { c } \text { Actual value } \\\text { (or) Y }\end{array} & \begin{array} { c } \text { Period number } \\\text { (or) X }\end{array} \\\hline \text { Period 1 } & 10 & 1 \\\hline \text { Period 2 } & 11 & 2 \\\hline \text { Period 3 } & 9 & 3 \\\hline \text { Period 4 } & 12 & 4 \\\hline \text { Period 5 } & 13 & 5 \\\hline \text { Period 6 } & 12 & 6 \\\hline \text { Period 7 } & 15 & 7 \\\hline\end{array}$$
The intercept of the trend line is 8.714,and the slope is 0.75.What is the forecast error for period 7?

A) 1.036
B) 8
C) 2.37
D) 5.714
E) 4.75