Using HP 12c or HP 12c Platinum for Cost Estimation with Linear Regression
Johnson’s Chair Company has experienced the following costs for the first 6 months of the year:
Johnson’s Chair Company has experienced the following costs for the first 6 months of the year:  
# Chairs Made 5,000 5,500 4,800 5,300 4,950 5,150 
Total
Costs $120,000 $122,100 $118,540 $122,400 $119,100 $124,200 
Entering data in HP 12c:

[f] [REG]

120,000 [ENTER] 5,000 [+]

122,100 [ENTER] 5,500 [+]

118,540 [ENTER] 4,800 [+]

122,400 [ENTER] 5,300 [+]

119,100 [ENTER] 4,950 [+]

124,200 [ENTER] 5,150 [+]
Johnson’s fixed cost (Even when no chair was build):

Press 0 then [g] [y,m]

Display 89,449.381 is the Answer
Johnson’s variable cost (cost of a single chair):

Press 1 then [g] [y,m]

Display 89,455.559

Deduct this with the above fixed cost 89,449.381

6.178 which is the cost for one unit of chair.
How good is the fit of the linear regression line generated?

Press 0 then [g] [y,m]

Press 1 then [Shift] [y,m]

Press [x<>y]

Display 0.716 this is the answer
Total costs for 5,400 chairs:

Enter 5,400 then press [g] [y,m]

Display 122,806.907 is the Answer.
Total costs were $125,000, how many chairs:

Enter 125,000 then press [g] [x,m]

Display 5,755.023 is the Answer.