Assume:

Store $1$:

Lead$-$Time Demand $($Throughput$,R_1)$ is $1,000$ units,

Lead$-$Time$-$Demand Standard Deviation $($STD $1)$ is $300$ units,

Store $2$:

Demand Rate $($Throughput$,R_2)$ is $2,000$ unit$/$day$,$

Demand Standard Deviation $(\{$:$ST{D}_2)$ is $400$ units,

What is the combined Lead$-$Time$-$Standard$-$Deviation?

units

Combined STD $=$ SQRT $(S_{TD}{1}^2+STD{2}^2)=$

SORT $({300}^{{?}^{?}}{?}^{+400}{?}^7)=500$ units

How is it $500$ units?