A cosmetics manufacturer's marketing department has analyzed sales from last 10 years of its popular Hand & Foot Cream product. In table 1 below, you will see sales per week during a period of 8 weeks. In table 2, you will see the sales forecasted using a linear regression formula that they got from table 1s data.

Table 1

week	1	2	3	4	5	6	7	8
sales	97	108	?	136	167	180	196	210

Table 2

week	-1	12
forecasted sales	57.97	280.214

1. Find the linear regression formula.

2. Predict Sales for week 18th using this linear regression equation.

3. Is it possible to find value 3 in table 1?