Texas Instruments MathPrint TI-30X Plus, Quick Manual

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22
(a) (iii) Company A
3 1
IQR Q Q 1.4
= − =
(grams)
(a) (iii) Company B
Repeat the above instructions ensuring
that
L2 is selected.
3 1
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
, a b
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 ).