Rajan is filling a basket with pears of equal weight. Draw a graph and write an equation to represent this situation.

The table shows the relationship between the number of pears and the total weight of the basket. After 1 pear, the total weight of the basket is 12 ounces. After 4 pears, the total weight is 39 ounces. Plot the two points on the graph to show the total weight of the basket of pears after 1 pear and 4 pears are put in the basket.
Number of pears Total weight (oz)
1 12
4 39
You got it!
For each pear added to the basket, the total weight increases at a constant rate. So, we can draw a line through these two points to show the linear relationship between the number of pears and the total weight in ounces. Let’s write an equation to represent this line in the form y=mx+b. Start by finding m, or the slope. What is the slope of this line?
x
y
(1, 12)(4, 39)
0
1
2
3
4
5
0
3
6
9
12
15
18
21
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27
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33
36
39
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48
Number of pears
Total weight (oz)
y= mx + b

Slope =

1 answer

To determine the slope \( m \) of the line that represents the total weight of the basket as a function of the number of pears, we can use the formula for the slope between two points:

\[ m = \frac{y_2 - y_1}{x_2 - x_1} \]

Where:

  • \( (x_1, y_1) = (1, 12) \)
  • \( (x_2, y_2) = (4, 39) \)

Now, substituting the coordinates into the slope formula:

\[ m = \frac{39 - 12}{4 - 1} = \frac{27}{3} = 9 \]

So the slope \( m = 9 \). This indicates that for each pear added, the total weight increases by 9 ounces.

Next, we can use one of the points to find the y-intercept \( b \). We'll use the point \( (1, 12) \) and the equation of a line in the form \( y = mx + b \).

Substituting \( x = 1 \), \( y = 12 \), and \( m = 9 \):

\[ 12 = 9(1) + b \]

This simplifies to:

\[ 12 = 9 + b \]

To solve for \( b \):

\[ b = 12 - 9 = 3 \]

So the y-intercept \( b = 3 \). Now we can write the equation that represents the relationship between the number of pears \( x \) and the total weight \( y \):

\[ y = 9x + 3 \]

Summary:

  • Slope (m): 9
  • Y-Intercept (b): 3
  • Equation: \( y = 9x + 3 \)

Graph:

To plot the graph:

  1. Mark the points \( (1, 12) \) and \( (4, 39) \).
  2. Draw a line through these points, extending in both directions. The line will have a steep positive slope.

Let me know if you need any further assistance!