She models the section from (0 , 3.5) to (4 , 6) as a straight line.(a) Find the equation of the line passing through these two points. [2]

To find the equation of the line passing through two points, we can use the formula for the slope of a line, which is (y2 - y1) / (x2 - x1), and the point-slope form of a line, which is y - y1 = m(x - x1).

Step 1: Calculate the slope (m) The slope of the line passing through the points (0 , 3.5) and (4 , 6) is (6 - 3.5) / (4 - 0) = 2.5 / 4 = 0.625.

Step 2: Use the point-slope form to find the equation of the line We can use either of the two points for this step. If we use the point (0 , 3.5), the equation of the line is y - 3.5 = 0.625(x - 0).

Simplifying this equation gives us the final equation of the line: y = 0.625x + 3.5.