The Jersey Store is a store that exclusively sells sports jerseys. These tend to have significant seasonality

depending on the sport. For instance, the sales for basketball jerseys peak in spring months, whereas more

football jerseys are usually sold in the fall. It makes it difficult to forecast quarterly demand for such

products having seasonality. The sales manager of The Jersey Store needs your help in this regard.

The following table shows the sales $($in thousands$)$ of their basketball jerseys from $2012$ to $2015$ by quarter.

Quarter $2012201320142015$

Winter $738840864774$

Spring $1050118210981020$

Summer $9013296108$

Fall $252384336234$

Total $2130253823942136$

a$.$ What method would you use to calculate this? Why?

b$.$ Calculate the forecast for $2016$