Estimate of variable electricity costs per machine hour

Question

Problem: Machine hours and electricity costs for Wells Industries for 2011 were as follows:

                      Machine      Electricity
Month               Hours          Costs
January            2,000         $ 9,200
February           2,320          10,500
March               1,520            6,750
April                 2,480           11,500
May                  3,040           14,125
June                 2,640           11,000
July                  3,280           12,375
August              2,800           11,375
September        1,600            7,750
October             2,960          13,000
November          3,760         15,500
December           3,360         13,875

Required:

Question 1: Using the high-low method, develop an estimate of variable electricity costs per machine hour.

Question 2: Using the high-low method, develop an estimate of fixed electricity costs per month.

Question 3: Using the high-low method, develop a cost function for monthly electricity costs.

Question 4: Estimate electricity costs for a month in which 3,000 machine hours are worked.