Problem: The ABC store has recorded sales $($in units$)$ for three products during the last $15$ workdays:

$\backslash$table$[[$Workday$,$Apple Laptop,Apple Watch,Apple Tablet$],[1,32,22,46],[2,36,21,27],[3,34,23,28],[4,36,23,24],[5,37,26,23],[6,32,27,49],[7,36,27,30],[8,38,29,21],[9,31,28,15],[10,33,30,19],[11,37,31,48],[12,33,32,27],[13,39,33,28],[14,36,34,25],[15,35,37,23],[16,,,]]$

a$)$ Plot the three time series variables to determine their pattern $($using Excel$).$

b$)$ Forecast workday $16$ sales for each of the products using an appropriate na$$ve method. And justify the each calculation using na$$ve method $($in each case$).$