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39
Predict
the
age of death of
a 6-foot
man weighing 190
pounds
in
1950.
190 I
sH1FT
I
rTI
73.4945283
years
To
reach
age
90,
what
should a
man'
s weight
be in 1960?
90
lstt1FT)[E)
160.3712108
pounds
To reach age 150,
what
should
a
man's weight
be?
Obviously, the answer will make
no sense, indicating
the
danger of carrying a straight-line extrapolation
too far.
321.9292125
(y-axis)
-1.795088908
(slope)
!SHIFT)
m
ISHIFT)W
-0.792926167
2.
1.
Display
0.
!SHIFT)~
72
M
185 ~
67@
226 ~
(Continue
to place in all data)
lsHIFTI
[r)
The value
for
r
indicates
a relatively
high negative
correlation.
A higher weight
means
a
shorter
lite
span.
To
graph the
regression
line, coefficients
a
and
b
are
used.
Weightatage65
185
226
200
169
170 195
175
174 198 172
9
10
7
8
5
6
4
3
2
Sample
72
67
69
85
91
68
77
74
70
82
Age at death
Example
2:
Is
weight
a
good predictor of
longevity
among men
65 years
of
age? In
1950, 10
men,
each six
feet tall,
were
selected for an
experiment
to
determine if
their
weight
effected
their life
span.
If
we
had
a
student
whose mark
in
mathematics
was
90, the student
would have a
mark
of
95
in English based on
this
anal
y
sis.
Display
95.33333333
Key
in:
90
I
SHIFT
I
[El
The value
of 0.571587901
for
r indicates
that the
correlation
is
moderate.
The
equation
for the
straight
line
for this data is
y
=
34:26
+
0.68x
when
truncated to
second decimal
places.
0.571587901
34.26190476 (y-axis)
0.678571428
(slope)
I
SHIFT!
[TI
I
SHIFT
I
[~Cl
!SHIFT!
m
Using
as a Calculator
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