Back to Assess fit by analyzing residuals — Problem 2 · Task Set 7

Exercises: Assess Fit by Analyzing Residuals

Work through each section in order. A residual is observed minus predicted: positive when the data point is ABOVE the model, negative when below. Keep the sign. When reading a residual plot, remember the key idea: random scatter around zero means a GOOD fit, while a clear pattern (a curve or a fan) means the model is wrong.

Grade 10·20 problems·~35 min·Common Core Math - HS Statistics and Probability·standard·hss-id-b-6b
Work through problems with immediate feedback
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Warm-Up: What Is a Residual?

These problems review the residual definition and its sign.

1.

A line y=0.10x+20y = 0.10x + 20 models a phone bill, where xx is minutes used. At x=50x = 50 minutes a customer was actually charged $26\text{\char"0024}26. The model predicts 0.10(50)+20=$250.10(50) + 20 = \text{\char"0024}25. What is the residual (observed - predicted) for this customer?