Math Problem Statement

Shen teaches a small history class. For several days, he recorded the number of filled seats and the number of open seats each day. Using x for the number of filled seats and y for the number of open seats, do the following: Plot the ordered pairs described by the table and write an equation relating x and y.

Solution

Let's break this down into two parts, as required by the question:

1. Plotting the Ordered Pairs:

The table gives the following ordered pairs (x,y)(x, y), where xx represents the number of filled seats and yy represents the number of open seats:

  • (3, 15)
  • (7, 11)
  • (8, 10)
  • (13, 5)

These pairs can be plotted on a coordinate plane, with xx on the horizontal axis and yy on the vertical axis.

2. Writing an Equation Relating xx and yy:

To find the equation, we assume the relationship between xx (filled seats) and yy (open seats) is linear. The general form of a linear equation is: y=mx+by = mx + b Where:

  • mm is the slope
  • bb is the y-intercept

Let's calculate the slope mm using the two points (3,15)(3, 15) and (13,5)(13, 5): m=y2y1x2x1=515133=1010=1m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{5 - 15}{13 - 3} = \frac{-10}{10} = -1

So, the slope is m=1m = -1.

Now, we can use one of the points to solve for the y-intercept bb. Using the point (3,15)(3, 15): 15=1(3)+b    15=3+b    b=1815 = -1(3) + b \implies 15 = -3 + b \implies b = 18

Thus, the equation relating xx and yy is: y=x+18y = -x + 18

Summary:

  • Ordered pairs: (3, 15), (7, 11), (8, 10), (13, 5)
  • Equation: y=x+18y = -x + 18

Would you like further details or help with graphing?

Here are 5 related questions:

  1. How do you calculate the slope between two points?
  2. What is the significance of the y-intercept in the equation?
  3. How can you use substitution to verify the equation?
  4. What would happen if the data were not linear?
  5. How can you determine if a system is over- or under-constrained?

Tip: Always check if a relationship appears linear before assuming a linear equation!

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Math Problem Analysis

Mathematical Concepts

Linear Equations
Slope-Intercept Form
Coordinate Geometry

Formulas

y = mx + b (Slope-Intercept Form)
m = (y2 - y1) / (x2 - x1) (Slope Formula)

Theorems

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Suitable Grade Level

Grades 6-8