You have been given the following quarterly sales data of 3 years for a store that sells big trucks for shipments

Quarter	2015	2016	2017
1	15	18	16
2	10	16	12
3	14	14	18
4	22	24	25

Part a) Choose the appropriate time series method and estimate the seasonal indices and adjusted forecast for each quarter if the annual demand is assumed to be 72. You can either create a table to present the numbers or just present them without a table in your response.

Part b) What are the limitations of qualitative models?