1. Write an equation of your line.
Approximating a Best-Fitting Line
Years since 1900
Distance (ft) 8 16 24 32 40 48 56 64 72 80 88 96
104
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
250
DISCUS THROWS
The winning Olympic discus throws from 1908 to 1996 are plotted in the graph. Approximate the best-fitting line for these throws.
Write an equation of your line.

2. Approximating a Best-Fitting Line
Years since 1900
Distance (ft) 8 16 24 32 40 48 56 64 72 80 88 96
104
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
250
SOLUTION
(96, 230).
(96, 230)
Find two points that lie on the best-fitting line, such as (8, 140) and (96, 230).
(8, 140)
Find the slope of the line through these points.

3. m = y = m x + b y = m x + b 140 = (1.02) (8) + b 138 for y.
Approximating a Best-Fitting Line
Years since 1900
Distance (ft) 8 16 24 32 40 48 56 64 72 80 88 96
104
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
250
(96, 230)
(8, 138)
y2 – y1
x2 – x1
m =
230 – 140
96 – 8 = 90 88
1.02
230 – 138
96 – 8 =
y = m x + b
Write slope intercept form.
Substitute 1.05 for m, 8 for x,
138 for y.
140 = (1.02) (8) + b 92 88 =
1.05
y = m x + b
140 = b
Simplify.
= b
Solve for b.
An equation of the best-fitting line is y = 1.02 x
In most years, the winner of the discus throw was able to throw the discus farther than the previous winner.