25.4 Scatter graphs and correlation — Practise

1. On two days, sunshine rises from $2$ hours to $5$ hours and ice cream sales rise from $12$ to $18$. State the direction of correlation.
2. A pupil studies for $3$ hours and scores $65$. Write the coordinate pair if hours are plotted first.
3. During a journey, time rises from $2$ minutes to $5$ minutes while distance remaining falls from $10$ km to $4$ km. State the direction of correlation.
4. A line of best fit passes through $(0,20)$ and $(8,60)$. Estimate $y$ when $x=5$.
5. In a sample, shoe size rises from $4$ to $6$ as reading age rises from $10$ to $12$. Does this prove that larger shoes cause higher reading ages?
6. A scatter graph contains $(1,3),(2,5),(3,2),(4,4)$, with no clear upward or downward pattern. Describe its correlation.
7. The observed $x$ values range from $2$ to $12$. Is an estimate at $x=8$ interpolation or extrapolation?
8. The observed $x$ values range from $2$ to $12$. Is an estimate at $x=16$ interpolation or extrapolation?
9. A scatter graph contains $(1,2),(2,4),(3,6),(4,8)$. Describe the direction and strength of the correlation.