Gilberto is baking brownies, so he turns the oven on. As soon as Gilberto turns the oven on, the oven heats up at a constant rate. Write an equation to represent this situation. Then use the equation to make a prediction.

This graph represents the linear relationship between the time in minutes and the temperature of the oven in degrees Fahrenheit. For each minute, the temperature increases at a constant rate. What do the points (2, 100) and (6, 220) represent?
x
y
(2, 100)(6, 220)
0
2
4
6
8
10
12
14
16
0
20
40
60
80
100
120
140
160
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220
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360
Time (minutes)
Temperature (°F)
The point (2, 100) means that after
minutes, the oven’s temperature was
degrees Fahrenheit.

The point (6, 220) means that after
minutes, the oven’s temperature was
degrees Fahrenheit.

1 answer

To represent the relationship between the time (in minutes) and the temperature (in degrees Fahrenheit) in an equation, we can use the linear equation of the form:

\[ y = mx + b \]

where:

  • \( y \) is the temperature,
  • \( x \) is the time in minutes,
  • \( m \) is the rate of change (temperature increase per minute),
  • \( b \) is the initial temperature of the oven (when \( x = 0 \)).

From the points given, we can determine the rate of change (\( m \)). We see that:

  • At \( (2, 100) \): After 2 minutes, the temperature is 100°F.
  • At \( (6, 220) \): After 6 minutes, the temperature is 220°F.

To find the rate of change, we calculate the slope \( m \):

\[ m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{220 - 100}{6 - 2} = \frac{120}{4} = 30 \]

Thus, the oven heats up at a rate of 30°F per minute.

Since we do not have the initial temperature (\( b \)), we can use one of the points to find it. Let's use the point \( (2, 100) \):

\[ 100 = 30(2) + b \] \[ 100 = 60 + b \] \[ b = 100 - 60 = 40 \]

So, the equation representing the relationship is:

\[ y = 30x + 40 \]

Now, regarding the points:

  • The point \( (2, 100) \) means that after 2 minutes, the oven’s temperature was 100 degrees Fahrenheit.

  • The point \( (6, 220) \) means that after 6 minutes, the oven’s temperature was 220 degrees Fahrenheit.

Using the equation, we can make a prediction. For example, to predict the temperature after 10 minutes:

\[ y = 30(10) + 40 = 300 + 40 = 340 \]

Thus, after 10 minutes, the predicted temperature of the oven would be 340 degrees Fahrenheit.