Math Problem Statement

The scatter plot shows the time spent studying, x, and the quiz score, y, for each of 24 students. Use the scatter plot to answer the parts below. (a) Write an approximate equation of the line of best fit. Round the coefficients to the nearest hundredth. (b) Using your equation from part (a), predict the quiz score for a student who spent 50 minutes studying. Round your prediction to the nearest hundredth.

Solution

Let's analyze the scatter plot and approximate the equation of the line of best fit. This equation will follow the general form y=mx+by = mx + b, where:

  • mm is the slope of the line.
  • bb is the y-intercept.

From the scatter plot:

  1. To find mm, select two points on the line of best fit (visually estimated).
  2. Calculate the slope mm using the formula: m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1}
  3. Use one of the points to solve for bb.

Next, I'll approximate the equation based on the visual appearance of the scatter plot.

Let's estimate two points from the plot:

  • Point 1: (10,20)(10, 20)
  • Point 2: (80,90)(80, 90)

Now, calculate the slope mm: m=90208010=7070=1m = \frac{90 - 20}{80 - 10} = \frac{70}{70} = 1

Use the slope and one of the points to find bb: y20=1(x10)y=1(x10)+20y=x+10y - 20 = 1(x - 10) \Rightarrow y = 1(x - 10) + 20 \Rightarrow y = x + 10

So, the approximate equation of the line is: y=x+10y = x + 10

Part (b): Predicting the Quiz Score

To predict the quiz score for a student who spent 50 minutes studying: y=50+10=60y = 50 + 10 = 60

Thus, the predicted quiz score is 60.

Would you like more details or explanations on any part of this? Here are some related questions that might interest you:

  1. What is a line of best fit, and why is it useful?
  2. How do you determine the accuracy of a line of best fit?
  3. What is the correlation coefficient, and how does it relate to scatter plots?
  4. How would the equation change if the points selected were different?
  5. What other methods can be used to find the equation of a line of best fit?

Tip: When approximating lines of best fit, choosing points that lie directly on the visualized line can improve accuracy.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Scatter Plots
Lines of Best Fit

Formulas

Equation of a line y = mx + b
Slope formula m = (y2 - y1) / (x2 - x1)

Theorems

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Suitable Grade Level

Grades 9-10