Question

9
equation of the trend line:

Explanation:

Step1: Find two points on the trend line

Let's take two points \((0,30)\) and \((20,40)\) from the trend - line.

Step2: Calculate the slope \(m\)

The slope formula is \(m=\frac{y_2 - y_1}{x_2 - x_1}\).
Substituting \(x_1 = 0,y_1=30,x_2 = 20,y_2 = 40\) into the formula:
\(m=\frac{40 - 30}{20-0}=\frac{10}{20}=\frac{1}{2}\)

Step3: Use the slope - intercept form \(y=mx + b\)

We know that when \(x = 0\), \(y=30\), so the \(y\) - intercept \(b = 30\).
The equation of the line in slope - intercept form \(y=mx + b\) becomes \(y=\frac{1}{2}x+30\)

Answer:

\(y=\frac{1}{2}x + 30\)