the annual profits for a company are given in the following table, where x represents the number of years…

the annual profits for a company are given in the following table, where x represents the number of years since 2006, and y represents the profit in thousands of dollars. write the linear regression equation that represents this set of data, rounding all coefficients to the nearest hundredth. using this equation, estimate the calendar year in which the profits would reach 482 thousand dollars.\n\n| years since 2006 (x) | profits (y) (in thousands of dollars) |\n| ---- | ---- |\n| 0 | 147 |\n| 1 | 167 |\n| 2 | 209 |\n| 3 | 239 |\n| 4 | 250 |\n| 5 | 267 |
Answer
Explanation:
Step1: Calculate the means of x and y
Let $x_i$ be the values of years since 2006 and $y_i$ be the profit - values. $n = 6$ $\bar{x}=\frac{\sum_{i = 1}^{n}x_i}{n}=\frac{0 + 1+2+3+4+5}{6}=\frac{15}{6}=2.5$ $\bar{y}=\frac{\sum_{i = 1}^{n}y_i}{n}=\frac{147 + 167+209+239+250+267}{6}=\frac{1289}{6}\approx214.83$
Step2: Calculate the slope (m)
$m=\frac{\sum_{i = 1}^{n}(x_i-\bar{x})(y_i - \bar{y})}{\sum_{i = 1}^{n}(x_i-\bar{x})^2}$ $(x_1-\bar{x})(y_1 - \bar{y})=(0 - 2.5)(147-214.83)=(-2.5)(-67.83)=169.575$ $(x_2-\bar{x})(y_2 - \bar{y})=(1 - 2.5)(167 - 214.83)=(-1.5)(-47.83)=71.745$ $(x_3-\bar{x})(y_3 - \bar{y})=(2 - 2.5)(209 - 214.83)=(-0.5)(-5.83)=2.915$ $(x_4-\bar{x})(y_4 - \bar{y})=(3 - 2.5)(239 - 214.83)=(0.5)(24.17)=12.085$ $(x_5-\bar{x})(y_5 - \bar{y})=(4 - 2.5)(250 - 214.83)=(1.5)(35.17)=52.755$ $(x_6-\bar{x})(y_6 - \bar{y})=(5 - 2.5)(267 - 214.83)=(2.5)(52.17)=130.425$ $\sum_{i = 1}^{n}(x_i-\bar{x})(y_i - \bar{y})=169.575+71.745 + 2.915+12.085+52.755+130.425=439.5$
$(x_1-\bar{x})^2=(0 - 2.5)^2 = 6.25$ $(x_2-\bar{x})^2=(1 - 2.5)^2=2.25$ $(x_3-\bar{x})^2=(2 - 2.5)^2 = 0.25$ $(x_4-\bar{x})^2=(3 - 2.5)^2=0.25$ $(x_5-\bar{x})^2=(4 - 2.5)^2 = 2.25$ $(x_6-\bar{x})^2=(5 - 2.5)^2=6.25$ $\sum_{i = 1}^{n}(x_i-\bar{x})^2=6.25+2.25 + 0.25+0.25+2.25+6.25 = 17.5$
$m=\frac{439.5}{17.5}\approx25.11$
Step3: Calculate the y - intercept (b)
$b=\bar{y}-m\bar{x}$ $b = 214.83-25.11\times2.5$ $b=214.83 - 62.78$ $b = 152.05$
The linear regression equation is $y = 25.11x+152.05$
Step4: Estimate the year when $y = 482$
Set $y = 482$ in the equation $482=25.11x+152.05$ $25.11x=482 - 152.05$ $25.11x=329.95$ $x=\frac{329.95}{25.11}\approx13.14$
The year is $2006 + 13.14\approx2019$ (rounding up to the next - whole year)
Answer:
The linear regression equation is $y = 25.11x+152.05$, and the profit would reach 482 thousand dollars in the year 2019.