The Brutus Gourmet Company produces delicious organic dog treats for canines with discriminating tastes. Management wants the box$-$filling line to be set so that the process average weight per packet is $127$ grams. To make sure that the process is in control, an inspector at the end of the filling line periodically selects a random box of $4$ packets and weighs each packet. When the process is in control, the range in the weight of each sample has averaged $8$ grams.

Sample size, n $=\_\_\_\_\_\_($enter whole number$).$