Question

Assume you have collected data pairs (x, y) on a certain variety of tree. x is

the number of weeks since the tree was planted and vis the height of the tree
in inches. A plot of the data points with the best-fit line is given below. What
age is predicted by the best-fit line for a height of 50 inches?
Height
+
20
40
100 120
60 80
Age​

Answer 1

Explanation:

The graph is a straight line graph.

Let find the equation of the straight line.

Equation of straight line is given as

y = mx + c

Where m is the slope and c is the intercept.

c is the intercept on y axis where x = 0.

Then, from the graph, where x = 0, y = 23.

Then, the intercept c = 24

First point is (0,24) and second point chosen is (80, 60)

The slope can be determined using

m = ∆y / ∆x = (60-25)/(80-0)

m = 0.4375

Then,

y = 0.4375x + 24

Then, we want to find the age (x) at height y = 50

50 = 0.4375x + 24

0.4375x = 50-24

0.4375x = 26

x = 26 / 0.4375

x =59.43 weeks

Directly from the graph the value is approximately 60weeks