Demand values for a product for the four more recent periods are shown below. Compute the Forecast for Period $5$ using a $3-$period Moving Average method.

Demand

$1$

$12$

$2$

$15$

$3$

$15$

$4$

$18$

Period $5$ Forecast $($using $3$ period Moving Average$)$: $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_($Use $2$ decimals$)$