Consider a three$-$firm supply chain consisting of a retailer, a manufacturer, and supplier. The demand for each is listed in the table below. Determine the variance for the retailer, the manufacturer, and the supplier. a$.$ What is the bullwhip measure for the manufacturer?

b$.$ What is the bullwhip measure for the supplier?

c$.$ Is there amplification or dampening of the bullwhip effect showing up in this data?