5-7 Scatter Plots and Trend Lines
V
Quick Review
A scatter plot displays two sets of d ata as ordered pairs. A
trend line for a scatter plot shows th e correlation betw een
th e two sets of data. The m ost accurate tren d line is th e line
of best fit. To estim ate or predict values on a scatter plot,
you can use in terpolation or extrapolation.1
Ex e r c i se s
Describe the type of correlation the scatter plot shows.
32.Ex a m p l e o
f. 33. 34.
•%••• • •••••*- • • • • • *
-----------------— 0 ---------------------- 0 - •
Estimate the length of the kudzu
vine in Week 3.
When w = 3, i = 10. So in Week 3,
the length of th e kudzu vine was
about 10 ft.
Predict the length of the kudzu
vine in Week 11.Kudzu Vine
Growth€ = 3 .5m; the trend line.Use the equation of- a. Make a scatter plot of th e data below.
Heights and Arm Spans
Height (m) 1.5 1.8 1.7 2 .0 1.7 2.1
Arm Span (m) 1.4 1.7 1.7 1.9 1.6 2 .0( = 3.5(11) Substitute 11 for w.
€ = 38.5 Simplify.
The length of the vine in Week 11 will be ab o u t 38.5 ft.5-8 Graphing Absolute Value Functions
b. W rite an eq u a tio n of a reasonable tren d line or
use a graphing calculator to find th e equation of
the line of best fit.
c. Estim ate th e arm sp an of som eone w ho is
1.6 m tall.
d. Predict th e arm span of som eone who is 2.2 m tall.Quick Review
The graph of an absolute value function is a V -shaped
graph th at opens upw ard or downward.
A translation shifts a graph either vertically, horizontally,
or both. To graph an absolute value function, you can
translate y = jx|.Ex a m p l e
Graph the absolute value function y = | x — 4 1.
Start w ith the graph
o fy = |x|. Translate
the graph right
4 units.Ex e r c i s e s
Graph each function by translating y = | x |.
36.y= |x| +2 37.y= I|x| - 7
38.y= |x + 3| 39.y= I- The table below shows th e incom e tax for a single
person's m onthly incom e. G raph th e step function
for this inform ation.
Tax Rates fo r Single Persons
r ................ ......
If M onthly Income Is...
....... .............. —^
Computed Tax is...$0—$504.00 0%
$504.01-5869.00 10%
$869.01-$3,004.00 15%
$3,004.01-$5,642.00 25%
$5,642.01-57,038.00 30%356 Ch ap t er 5 Ch ap t er Revi ew