Statistics as a Problem-Solving Process and the Role of Questioning — Test
Question 7 • Statistical Reasoning
Market researchers were interested in the relationship between the number of pieces in a brick-building set and the cost of a set. Information was collected from a survey and was used to obtain the regression equation widehat y is equal to 0 point 0 8 x plus 1 point 2 0 , where x represents the number of pieces in a set and widehat y is the predicted price (in dollars) of a set. Which statement best describes the meaning of the y - intercept of the regression line?
Answer
A
When the number of pieces is 0 , the predicted price is 0 point 0 8 dollars . This interpretation is not meaningful because a set cannot have 0 pieces.
B
When the price of a set is 0 dollars , the predicted number of pieces is 1 point 2 0 .
C
When the price of a set is 0 dollars , the predicted number of pieces is 0 .
D
When the number of pieces is 0 , the predicted price is 1 point 2 0 dollars . This interpretation is not meaningful because a set cannot have 0 pieces.
Explanation
In the regression equation, the y-intercept is the predicted price when x, the number of pieces, is 0. Substituting x = 0 gives a predicted price of $1.20; this interpretation is not meaningful because a set cannot have 0 pieces, so choice B is correct.
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