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Lesson 4: Modeling with Quadratic Functions — Practice Questions

  1. 1. For the data point $(3, 10)$, what is the residual for the quadratic model $y = x^2 - x + 3$? The residual is ___.

  2. 2. When analyzing a residual plot for a quadratic regression, which observation suggests that the quadratic model is a good fit for the data?

    • A. The residuals form a clear U-shaped curve.
    • B. The residuals are all positive.
    • C. The residuals are randomly scattered around the horizontal axis.
    • D. The residuals form a straight line with a positive slope.
  3. 3. A quadratic model $y = -x^2 + 3x + 2$ is used to fit a set of data. If one of the actual data points is $(2, 5)$, the corresponding residual is ___.

  4. 4. A statistician creates a residual plot after fitting a quadratic model to a dataset. If the plot shows a distinct curved pattern, what is the most likely conclusion?

    • A. The quadratic model is a perfect fit.
    • B. The quadratic model is a good fit.
    • C. The quadratic model may not be the best choice for this data.
    • D. The data contains no errors.
  5. 5. A residual plot is created for the model $y = x^2 + x$. For the data point $(4, 22)$, the corresponding point on the residual plot is $(4, \text{\_\_\_})$.

  6. 6. A quadratic regression model has a coefficient of determination of $R^2 = 0.88$. What does this value indicate about the model?

    • A. The model explains 12% of the variation in the data.
    • B. The model explains 88% of the variation in the data.
    • C. The model is a perfect fit for the data.
    • D. The model is a poor fit for the data.
  7. 7. If a quadratic model has a coefficient of determination of $R^2 = 0.97$, what percentage of the variation in the data does the model explain? The answer is ___%.

  8. 8. A researcher creates two models for a dataset. Model A has $R^2 = 0.91$ and Model B has $R^2 = 0.65$. Which statement correctly compares the two models?

    • A. Model B is a better fit than Model A.
    • B. Model A is a better fit than Model B.
    • C. Both models fit the data equally well.
    • D. Neither model is a particularly good fit.
  9. 9. A student performs a quadratic regression and finds that $R^2 = 0.35$. What is the most appropriate conclusion to draw?

    • A. The quadratic model is an excellent fit.
    • B. The model explains 65% of the data's variation.
    • C. The data points form a perfect parabola.
    • D. The quadratic model may not be appropriate for this data.
  10. 10. For a set of data points that lie perfectly on a parabola, what would be the coefficient of determination, $R^2$, for the quadratic model? The value would be exactly ___.