1. **State the problem:** We have air temperature data at various altitudes and want to analyze the correlation, draw a line of best fit, and estimate temperature at 1500 m. 2. **Data points:** Altitude (m): $0, 300, 800, 1000, 1400, 1600, 1800, 2000$ Temperature (°C): $18, 14, 10, 8, 4, 3, 2, 0$ 3. **Correlation type:** Observing the data, as altitude increases, temperature decreases. This indicates a **negative correlation**. 4. **Line of best fit formula:** We use the linear equation $y = mx + b$ where $y$ is temperature and $x$ is altitude. 5. **Calculate slope $m$:** Using points $(0,18)$ and $(2000,0)$, $$m = \frac{0 - 18}{2000 - 0} = \frac{-18}{2000} = -0.009$$ 6. **Calculate intercept $b$:** Using point $(0,18)$, $$b = 18$$ 7. **Line of best fit equation:** $$y = -0.009x + 18$$ 8. **Estimate temperature at 1500 m:** $$y = -0.009 \times 1500 + 18 = -13.5 + 18 = 4.5$$ **Final answer:** The correlation is negative. The estimated temperature at 1500 m is $4.5$ °C.