Cambridge International Mathematics

26 Graphics calculator instructions

ZOOM 6:ZStandard: This command returns the viewing window to the

default setting of ¡ 106 x 610 ,¡ 106 y 610 :

If neither of these commands are helpful, the viewing window can be adjusted

manually by pressing WINDOW and setting the minimum and maximum

values for thexandyaxes.

Casio fx-9860g

The viewing window can be adjusted by pressing SHIFT F3 (V-Window).

You can manually set the minimum and maximum values of thexandyaxes,

or press F3 (STD) to obtain the standard viewing window

¡ 106 x 610 , ¡ 106 y 610 :

LINE OF BEST FIT

We can use our graphics calculator to find the line of best fit connecting two variables. We can also find

the values of Pearson’s correlation coefficientrand the coefficient of determinationr^2 , which measure the

strength of the linear correlation between the two variables.

We will examine the relationship between the variablesxandyfor the data:

x 1 2 3 4 5 6 7

y 5 8 10 13 16 18 20

Texas Instruments TI-84 Plus

Enter thexvalues intoList 1and theyvalues intoList 2using the instructions

given on page 19.

To produce a scatter diagram of the data, press 2nd Y=

(STAT PLOT) 1 , and set upStatplot 1as shown.

Press ZOOM 9 : ZoomStat to draw the scatter diagram.

We will now find the line of best fit. Press STAT I

4:LinReg(ax+b)to select the linear regression option from the CALC menu.

Press 2nd 1(L 1 ) , 2nd 2(L 2 ) , VARS I 11 (Y 1 ). This specifies

the listsL 1 andL 2 as the lists which hold the data, and the line of best fit will

be pasted into the functionY 1 :Press ENTER to view the results.

The line of best fit is given as y¼ 2 : 54 x+2: 71 : If therandr^2 values are

not shown, you need to turn on the Diagnostic by pressing2nd 0 (CATALOG)

and selectingDiagnosticOn.

H TWO VARIABLE ANALYSIS

IGCSE01

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Y:\HAESE\IGCSE01\IG01_00a\026IGCSE01_00a.CDR Tuesday, 4 November 2008 9:53:42 AM PETER