Question $40(5$ points$)$

Below you are given the first two values of a time series. You are also given the first two values of the exponential smoothing forecast.

$\backslash$table$[[$Time Period $(t),$Time Series Value $(Yt),\backslash$table$[[$Exponential$],[$Smoothing$],[$Forecast $($Ft$)]]],[1,15,15],[2,25,15],[3,,]]$

If the smoothing constant equals $\mathrm{.}4,$ then the exponential smoothing forecast for time period three is

a$)10$

b$)20$

c$)15$

d$)19$