Suppose that the water level of a river is 34 feet after 3 days of rain and 62 feet after 10 days of rain. The river was 22 feet before the rain began.

a. What is the rate of change (slope) for this scenario? _____________
b. What is the y-intercept for this scenario? ____________
c. Write an equation for the scenario in slope-intercept form. ______________
d. Write this equation in standard form. _____________
Options: -4x + y = 34, (0, 34), y = 4x - 22, -4 + y = 22, 4, y = 28x + 34, 7, (0, 0), y = 4x + 34, 22, 0, 4x + y = 34, (0, 22), y = 4x + 22, 28, (0, 4)

1 answer

To solve the problem, let's analyze the information provided step by step.

a. Rate of Change (Slope)

The slope can be calculated using the formula for slope (m): \[ m = \frac{y_2 - y_1}{x_2 - x_1} \]

Here:

  • \(y_1 = 34\) feet (after 3 days)
  • \(y_2 = 62\) feet (after 10 days)
  • \(x_1 = 3\) days
  • \(x_2 = 10\) days

Calculating the slope: \[ m = \frac{62 - 34}{10 - 3} = \frac{28}{7} = 4 \]

Answer a: The rate of change (slope) for this scenario is 4.

b. Y-Intercept

Now we will find the y-intercept. The y-intercept is the starting value (when \(x = 0\)). Before the rain began, the river was at a level of 22 feet.

Answer b: The y-intercept for this scenario is 22.

c. Equation in Slope-Intercept Form

The general form of the slope-intercept equation is: \[ y = mx + b \] Where:

  • \(m\) is the slope (which we found to be 4)
  • \(b\) is the y-intercept (which we found to be 22)

Thus, the equation becomes: \[ y = 4x + 22 \]

Answer c: The equation for the scenario in slope-intercept form is \(y = 4x + 22\).

d. Equation in Standard Form

To write the equation \(y = 4x + 22\) in standard form \(Ax + By = C\), we rearrange it: \[ -4x + y = 22 \] Alternatively, we can multiply through by -1 for a different standard form: \[ 4x - y = -22 \] However, both versions are standard forms.

One of the standard forms using the option choices is \( -4x + y = 22\).

Answer d: The equation in standard form is \(-4x + y = 22\).

Summary of Answers:

  • a: 4
  • b: 22
  • c: \(y = 4x + 22\)
  • d: \(-4x + y = 22\)