1. **State the problem:** We need to find the correlation coefficient $r$ for the data pairs $(x, y)$ where $x$ is the number of breakfasts eaten and $y$ is the GPA.
2. **Recall the formula for the correlation coefficient:**
$$r = \frac{n\sum xy - \sum x \sum y}{\sqrt{(n\sum x^2 - (\sum x)^2)(n\sum y^2 - (\sum y)^2)}}$$
where $n$ is the number of data points.
3. **List the data points:**
$$(6, 2.8), (9, 2.0), (11, 1.8), (13, 2.0), (24, 3.9), (28, 2.5)$$
4. **Calculate sums:**
- $n = 6$
- $\sum x = 6 + 9 + 11 + 13 + 24 + 28 = 91$
- $\sum y = 2.8 + 2.0 + 1.8 + 2.0 + 3.9 + 2.5 = 14.999999999999998 \approx 15.0$
- $\sum x^2 = 6^2 + 9^2 + 11^2 + 13^2 + 24^2 + 28^2 = 36 + 81 + 121 + 169 + 576 + 784 = 1767$
- $\sum y^2 = 2.8^2 + 2.0^2 + 1.8^2 + 2.0^2 + 3.9^2 + 2.5^2 = 7.84 + 4 + 3.24 + 4 + 15.21 + 6.25 = 40.54$
- $\sum xy = (6)(2.8) + (9)(2.0) + (11)(1.8) + (13)(2.0) + (24)(3.9) + (28)(2.5) = 16.8 + 18 + 19.8 + 26 + 93.6 + 70 = 244.2$
5. **Plug values into the formula:**
$$r = \frac{6(244.2) - (91)(15)}{\sqrt{(6(1767) - 91^2)(6(40.54) - 15^2)}}$$
6. **Calculate numerator:**
$$6 \times 244.2 = 1465.2$$
$$91 \times 15 = 1365$$
$$\text{Numerator} = 1465.2 - 1365 = 100.2$$
7. **Calculate denominator parts:**
$$6 \times 1767 = 10602$$
$$91^2 = 8281$$
$$6 \times 40.54 = 243.24$$
$$15^2 = 225$$
8. **Calculate denominator:**
$$\sqrt{(10602 - 8281)(243.24 - 225)} = \sqrt{2321 \times 18.24}$$
9. **Calculate product inside square root:**
$$2321 \times 18.24 = 42356.64$$
10. **Square root:**
$$\sqrt{42356.64} \approx 205.8$$
11. **Calculate $r$:**
$$r = \frac{100.2}{205.8} \approx 0.487$$
**Final answer:** The correlation coefficient rounded to the nearest thousandth is **$r = 0.487$**.
Correlation Coefficient F11875
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.