# 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.

- 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) - 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*= 0.85*x*+ 2.15

**B.***y*= 1.7*x*+ 2.15

**C.***y*= 0.85*x*+ 1.3

**D.***y*= 1.7*x*+ 1.3

## Answers and Explanations

- 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). - 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 youTherefore, the equation is

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