Pane of Glass Inc. produces custom glasswork for high-end homes and buildings. The following cost data relate to the companys labour costs.

	Units Produced	Labour Cost
July	400	$15,000
August	300	13,000
September	320	13,200
October	350	13,800
November	420	16,000
December	410	14,800

Required:

1. Using the high-low method, estimate the cost formula (write it in y=mx+b format).
   1. Using your answer from part a.) above, assuming in the following month the company expects to make 250 units, what will be the companys estimated labour cost.
2. Using the scattergraph method, estimate the cost formula.
3. Using the least squares regression method, estimate the cost formula.
4. Are there any factors other than the number of units produced that may contribute to a variation in labour cost?