A homeowner records the outside temperature and the number of units of gas used for heating over 10 days. The scatter graph shows this information.
| Temperature (°C) | Gas used (units) |
|---|---|
| 2 | 45 |
| 4 | 38 |
| 6 | 32 |
| 8 | 28 |
| 10 | 22 |
| 12 | 17 |
| 14 | 12 |
| 16 | 5 |
| 18 | 2 |
| 4 | 5 |
What type of correlation does the scatter graph show?
One of the points is an outlier. Write down the coordinates for this point.
On another day the temperature was 9°C. Estimate the gas used on this day.
