The sales figures of a bicyde retailer in a city are given following

Forecast sales using

1. Naive method and find the root mean square error. (1+2)
2. Three month moving average method and find the root mean square error. (2+2)
3. Exponential smoothening constant method using a smoothening constant = 0.2

\begin{tabular}{|c|c|} \hline Period & \begin{tabular}{c} No of \\ bicycles sold \end{tabular} \\ \hline Dec-20 & 100 \\ \hline Jan-21 & 110 \\ \hline Feb-21 & 150 \\ \hline Mar-21 & 200 \\ \hline Apr-21 & 225 \\ \hline May-21 & 200 \\ \hline Jun-21 & 175 \\ \hline \end{tabular}