Chili Production B8B588
1. **Stating the problem:**
We have the production data of chili peppers (cabai) in tons from 2001 to 2012. We need to find:
a. The linear regression equation using the least squares method.
b. The estimated production for the year 2017 and a conclusion.
2. **Formula and explanation:**
The least squares regression line is given by:
$$y = a + bx$$
where:
- $y$ is the dependent variable (production),
- $x$ is the independent variable (year, transformed),
- $b = \frac{n\sum xy - \sum x \sum y}{n\sum x^2 - (\sum x)^2}$ is the slope,
- $a = \bar{y} - b\bar{x}$ is the intercept.
We transform years to $x$ by setting $x = \text{year} - 2000$ to simplify calculations.
3. **Data transformation and calculations:**
| Year | $x$ | Production $y$ (tons) |
|------|-----|-----------------------|
| 2001 | 1 | 861150 |
| 2002 | 2 | 766572 |
| 2003 | 3 | 762795 |
| 2004 | 4 | 757399 |
| 2005 | 5 | 732609 |
| 2006 | 6 | 794931 |
| 2007 | 7 | 802810 |
| 2008 | 8 | 853615 |
| 2009 | 9 | 965164 |
| 2010 | 10 | 1048934 |
| 2011 | 11 | 893124 |
| 2012 | 12 | 964221 |
Calculate sums:
$$n = 12$$
$$\sum x = 1+2+\cdots+12 = 78$$
$$\sum y = 861150 + 766572 + \cdots + 964221 = 10063004$$
$$\sum x^2 = 1^2 + 2^2 + \cdots + 12^2 = 650$$
$$\sum xy = 1\times861150 + 2\times766572 + \cdots + 12\times964221 = 68629554$$
4. **Calculate slope $b$:**
$$b = \frac{12 \times 68629554 - 78 \times 10063004}{12 \times 650 - 78^2} = \frac{823554648 - 785000312}{7800 - 6084} = \frac{38554336}{1716} \approx 22477.5$$
5. **Calculate intercept $a$:**
$$\bar{x} = \frac{78}{12} = 6.5$$
$$\bar{y} = \frac{10063004}{12} \approx 838583.7$$
$$a = 838583.7 - 22477.5 \times 6.5 = 838583.7 - 146103.75 = 692479.95$$
6. **Regression equation:**
$$y = 692479.95 + 22477.5x$$
7. **Estimate production for 2017:**
For 2017, $x = 2017 - 2000 = 17$
$$y = 692479.95 + 22477.5 \times 17 = 692479.95 + 382117.5 = 1074597.45$$
8. **Conclusion:**
The estimated chili production in 2017 is approximately 1,074,597 tons, showing an increasing trend in production over the years.