Arizona Crystal is a distributor of feldspar, amethyst and other mystically powerful types of crystals. The owner of Arizona Crystal, Geri Moonbeam, is proud to be a part of the movement that is contributing to the higher spirituality of the world. Geri buys crystals from local collectors and then ships them out to wholesalers throughout the country. Geri pays cash for the crystals, but she extends credit to the wholesalers.

As the business has grown, problems have arisen. When Geri buys more crystals than she can sell, inventory increases and cash flow problems arise. When Geri doesn't buy enough crystals, then she can't fill orders and that creates problems with her customers. She needs to base her buying decisions on accurate forecasts of the demand for crystals so she can avoid these problems.

After consulting her tarot cards, Geri visits a friend from El Paso, Texas, who channels for a Wall Street tycoon who didn't survive the crash of 1929. He recommends that, since she only has twelve months of data, she should try using a moving average or exponential smoothing forecasting model. So Geri contacts you. She provides you with data on the number of crystals (in thousands) ordered during each of the past twelve months and asks you to help her develop a forecasting model. To do so, solve Problems 7 through 11 below.

1)Use a three period moving average model to forecast the demand in January of 1993. Also calculate the RMSE for this model. Use the table below: