Teacher edition (with key)← Data analysis: two variables

Data analysis: two variables

High School Math 1 · Unit 18 · bivariate-regression

bivariate-regression

Name ______________________________Date ______________

1.
A survey asked students how they get to school.

Bus Walk
Grade 6 $18$ $12$
Grade 7 $24$ $6$

What percent of the grade 7 students walk? Enter the number only.
Answer: ______________
2.
A line of best fit is $\hat y = 2.5x + 10$ . One data point is $(6, 22)$ . What is the residual for this point?
Answer: ______________
3.
For a class, the line $\hat y = 3.2x + 15$ predicts a test score $y$ from hours of study $x$ . Which is the best interpretation of the number $3.2$ ?
1. (A)
  The predicted score for a student who studies $0$ hours
2. (B)
  The correlation between study time and score
3. (C)
  Each additional hour of study predicts about $3.2$ more points
4. (D)
  Every student's score rises exactly $3.2$ points per hour
4.
In a study of elementary-school children, shoe size and reading score have correlation $r = 0.2$ . Which statement is the best conclusion?
1. (A)
  There is a strong positive relationship, so bigger feet cause better reading
2. (B)
  There is a weak positive association; something else, such as age, could explain both
3. (C)
  Since $r > 0$ , $20\%$ of a child's reading score is explained by shoe size
4. (D)
  There is no association, because $r$ is less than $0.5$
5.
A line is fitted to data on a plant's height over $30$ days. In the residual plot, the residuals are positive for the first $8$ days, negative from day $9$ to day $22$ , and positive again after day $22$ , forming a U-shaped curve. Which conclusion is best?
1. (A)
  A linear model is not appropriate; the curved pattern means the relationship is not linear
2. (B)
  The linear model fits well because the residuals are both positive and negative
3. (C)
  The correlation $r$ must be exactly $0$
4. (D)
  The slope of the fitted line must be negative

	Bus	Walk
Grade 6	$18$	$12$
Grade 7	$24$	$6$