GED Math Extra Prep: Points, Lines, and Slopes

Some questions on the GED Math text will ask you to plot points based on information in a chart, or you may need to find the slope of a line using the slope formula. The following practice questions offer a typical example of each type of problem.

Practice Questions

Both questions are based on the following information.

Denise measures the height of a sunflower every other week over a three-month period and records the results in the following table.

1. Denise plots the data on a coordinate grid. She begins by plotting the data for Week 3 and Week 11. What are the coordinates of the two points that Denise plots?

   A. (11,3) and (11.5, 4.7) B. (3, 11) and (4.7, 11.5) C. (3, 4.7) and (11, 11.5) D. (4.7, 3) and (11.5, 11)

2. Denise creates an equation that will allow her to predict the height of the sunflower in the future, where x is the week and y is the height. Which of the following gives the correct equation?

   A. y = 0.85x + 2.15 B. y = 1.7x + 2.15 C. y = 0.85x + 1.3 D. y = 1.7x + 1.3

Answers and Explanations

1. The correct answer is C.

   By plotting the number of weeks along the x-axis and the height along the y-axis, Denise will place data points in the correct location on the coordinate grid: (3, 4.7) and (11, 11.5).

2. The correct answer is A.

   Find the slope, m, by substituting the coordinates of two data points listed in the table into the slope formula:

   

   Using the points (3, 4.7) and (11, 11.5), for example, gives you

   

   Because you now know the slope, you can calculate the y-intercept (b) by substituting any of the data points into the given equation. For example, using (1, 3.0) gives you

   

   Therefore, the equation is y = 0.85x + 2.15, making Choice (A) the correct answer.