$2.($Continued from question $2)$ The three product managers have decided to aggregate and order all three types each time they place an order.

a$.$ Evaluate the optimal order quantity $($lot size$)$ for each type $($keep one decimal if needed$).(3$pt$)$

b$.$ What is the total annual cost including fixed ordering cost, variable ordering cost, and inventory holding cost for the company $($keep $2$ decimals if needed$)?(2$pt$)$

c$.$ Quantify using the total annual cost from Q$1$ c$)$ and Q$2$ b$)$ the impact of coordinated replenishment. Shall the managers coordinate their orders? $(2$pt$)$