### Using HP 50g for Cost Estimation with Linear Regression

Entering data in HP 50g:

Press [Right Shift] [5] (STAT) and select {3. Fit data..} see Screen 1.

To access FIT DATA Form Press soft key {EDIT} (F1). Enter the data as show on see Screen 2.

Enter the the following into the Column 1

5,000

5,500

4,800

5,300

4,950

5,150

And into Column 2

120,000

122,100

118,540

122,400

119,100

124,200

What is Johnson’s fixed cost:

• Press [ON] key a couple to times

• Press [Right Shift] [5] (STAT) and select {3. Fit data..} to access FIT DATA Form

• Press soft key {PRED} to access PREDICT DATA Form (see Screen 3)

• Use the [Down] key a couple of times to move to X:

• Enter 0 and press [ENTER]

• The cursor with hop to Y: field

• Press soft key {PRED}

• Press soft key {EDIT} to display the number

It should show 89,449.3814433 which is the Answer. (see Screen 4)

Johnson’s variable cost (cost to build one chair):

• Use the [Down] key a couple of times to move to X:

• Display PREDY(

• Enter 1 and press [ENTER]

• Display 89,455.5587629 is the Answer.

• 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 [ON] to exit FIT DATA form (see Screen 5)

The Correlation will be displayed

It should show 0.716220427081

0 is worst and 1 is best, so 0.7 is fairly good.

Total costs for 5,400 chairs:

• Press [ON] key a couple to times

• Press [Right Shift] [5] (STAT) and select {3. Fit data..} to access FIT DATA Form

• Press soft key {PRED} to access PREDICT DATA From

• Use the [Down] key a couple of times to move to X:

• Enter 5400 and press [ENTER]

• The cursor with hop to Y: field

• Press soft key {PRED}

• Press soft key {EDIT} to display the number

It should show 122,806.907216 which is the Answer.

Total costs were \$125,000, how many chairs:

• Press [ON] key a couple to times

• Press [Right Shift] [5] (STAT) and select {3. Fit data..} to access FIT DATA Form

• Press soft key {PRED} to access PREDICT DATA From

• Use the [Down] key a couple of times to move to Y:

• Enter 125,000 and press [ENTER]

• The cursor with hop to X: field

• Press soft key {PRED}

• Press soft key {EDIT} to display the number

It should show 5,755.02336448 which is the Answer.

With Graphing Calculator you can chart the above solution.

• Press [Left Shift] [2D/3D] to access PLOT SETUP Form. (see Screen 1)

• Choose the Scatter Chart.

• Press [Left Shift] [WIN] to access PLOT WINDOW Form. (see Screen 2)

• Press the top soft key {AUTO} [F4] button.

• Press the top soft key {DRAW} [F6] button.

• This will display all the points (see Screen 3).

• To draw the Linear Curve Fit press the top soft key {STATL} (see Screen 4).

This solution is also applicable to HP 49g, HP 49g+ Graphing Calculator.