The annual profits for a company are given in the following table, where x represents the number of years since 2012, 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 234 thousand dollars.

The annual profits for a company are given in the following table where x represents the number of years since 2012 and y represents the profit in thousands of class=

Respuesta :

Regression Equation:y=17x+103.5

Final Answer:274 thousand dollars

Using line of best-fit, it is found that:

  • The linear regression equation is [tex]y = 22.6x + 52.33[/tex]
  • The profit would reach 234 thousand dollars during the calendar year of 2020.

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The line of best-fit is given by:

[tex]y = bx + a[/tex]

  • The slope is:

[tex]b = \frac{\sum (x-\overline{x})(y - \overline{y})}{\sum (x - \overline{x})^2}[/tex]

  • With the slope, we replace y and x by their means in the line, to find a.

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  • The means are:

[tex]\overline{x} = \frac{0 + 1 + 2 + 3 + 4 + 5}{6} = 2.5[/tex]

[tex]\overline{y} = \frac{38 + 92 + 98 + 119 + 147 + 159}{6} = 108.8[/tex]

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  • The sums are:

[tex]\sum x - \overline{x} = (0 - 2.5) + (1 - 2.5) + ... (5 - 2.5)[/tex]

[tex]\sum y - \overline{y} = (38 - 108.8) + ... (159 - 108.8)[/tex]

Using a calculator:

[tex]\sum (x-\overline{x})(y - \overline{y}) = 395.5[/tex]

[tex]\sum (x - \overline{x})^2 = 17.5[/tex]

Thus, the slope is:

[tex]b = \frac{\sum (x-\overline{x})(y - \overline{y})}{\sum (x - \overline{x})^2} = \frac{395.5}{17.5} = 22.6[/tex]

Then

[tex]y = 22.6x + a[/tex]

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Replacing the means, the intercept a is given by:

[tex]108.8 = 22.6(2.5) + a[/tex]

[tex]a = 108.8 - 22.6(2.5)[/tex]

[tex]a = 52.33[/tex]

Thus, the linear regression equation is:

[tex]y = 22.6x + 52.33[/tex]

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  • The profit will reach 234 thousand dollars in x years after 2012, and x is found when y = 234, thus:

[tex]y = 22.6x + 52.33[/tex]

[tex]234 = 22.6x + 52.33[/tex]

[tex]22.6x = 234 - 52.33[/tex]

[tex]x = \frac{234 - 52.33}{22.6}[/tex]

[tex]x = 8.03[/tex]

2012 + 8 = 2020

The profit would reach 234 thousand dollars during the calendar year of 2020.

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