Common Core: S-ID.8
Problem 10 of 45s12-010
For 40 used cars, the correlation between age (in years) and price (in dollars) is . Which statement correctly interprets ?
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Solution walkthrough1:48
- The correlation measures the direction and strength of a linear pattern. It is always from to .
- The sign is negative, so as age goes up, price tends to go down: older cars tend to cost less.
- The size, , is close to , so the pattern is strong: the points sit fairly close to a straight line.
- has no units. Writing price in thousands of dollars moves no point, so stays .
- Traps: the sign gives direction, not strength. Do not drop the minus sign. Changing units never changes .