We have the following observed series: $($Beta $=\mathrm{.}2)$

Period

Observed

$1$

$150$

$2$

$180$

$3$

$170$

$4$

$150$

$5$

$175$

$6$

$180$

$7$

$200$

$8$

$230$

$9$

$240$

$10$

$250$

$11$

$260$

$12$

$240$

Using Adaptive Response Smoothing technique, find the forecast series and then calculate the MAPE. The MAPE is:

$8\mathrm{.}43\%$

$7\mathrm{.}47\%$

$10\mathrm{.}09\%$

$8\mathrm{.}05\%$