Texas Instruments MathPrint TI-30X Plus - Keyboard Shortcuts: TI-30 X Pro;Plus

22
(a) (iii) Company A
31
IQR Q Q 1.4= − =
(grams)
(a) (iii) Company B
Repeat the above instructions ensuring
that L2 is selected.
31
IQR Q Q 0.6= − =
(grams)
(b)
Company A produces packets of chips
with a weight centred closer to
50
grams
than Company B, but with greater variation
(using the
IQR
) in the weights. Company
B produces packets of chips centred
slightly greater than
50
grams whereas
some of the packets produced by
Company A are less than
50
grams.
Example
The length measurements (correct to the nearest cm) of the femur bone and humerus bone
of a particular species of fossil are shown in the following table.
Femur length (
x
)
60
57
65
39
75
Humerus length (
y
)
71
64
73
42
85
(a) Use the TI-30X Plus MathPrint™ to determine the least-squares regression line. Give
your answer in the form
y ax b=+
where
,ab
are expressed correct to two decimal
places.
(b) Use the least-squares regression line found in part (a) to estimate the length of a
humerus bone of this species of fossil whose femur length is
48
cm. Give your
answer correct to the nearest centimetre.
Keystrokes and solution:
Using the data editor and list formulas
feature:
Press .
Press   to clear all lists.
Enter the femur bone lengths in L1. Start
by entering
60
and pressing ] (n).