Suppose That We Calculate the Four-Period Moving Average of the Following

Multiple Choice

Suppose that we calculate the four-period moving average of the following time series: $$\begin{array} { | c | c c c c c c | } \hline t & 1 & 2 & 3 & 4 & 5 & 6 \\\hline y _ { t } & 18 & 28 & 23 & 17 & 26 & 14 \\\hline\end{array}$$ The centred moving average for period 4 is:

A) 20.00.
B) 22.50.
C) 23.50.
D) 21.75.