the number of newly reported crime cases in a county in new york state is shown in the accompanying table…

the number of newly reported crime cases in a county in new york state is shown in the accompanying table, where x represents the number of years since 2013, and y represents number of new cases. write the linear regression equation that represents this set of data, rounding all coefficients to the nearest tenth. using this equation, estimate the calendar year in which the number of new cases would reach 604.\n\n|years since 2013 (x)|new cases (y)|\n|----|----|\n|0|816|\n|1|802|\n|2|809|\n|3|780|\n|4|754|\n|5|712|

the number of newly reported crime cases in a county in new york state is shown in the accompanying table, where x represents the number of years since 2013, and y represents number of new cases. write the linear regression equation that represents this set of data, rounding all coefficients to the nearest tenth. using this equation, estimate the calendar year in which the number of new cases would reach 604.\n\n|years since 2013 (x)|new cases (y)|\n|----|----|\n|0|816|\n|1|802|\n|2|809|\n|3|780|\n|4|754|\n|5|712|

Answer

Explanation:

Step1: Calculate the means of x and y

Let $n = 6$. $\bar{x}=\frac{0 + 1+2+3+4+5}{6}=\frac{15}{6}=2.5$ $\bar{y}=\frac{816 + 802+809+780+754+712}{6}=\frac{4673}{6}\approx778.8$

Step2: Calculate the slope $m$

[ \begin{align*} m&=\frac{\sum_{i = 1}^{n}(x_i-\bar{x})(y_i - \bar{y})}{\sum_{i=1}^{n}(x_i-\bar{x})^2}\ \sum_{i = 1}^{6}(x_i-\bar{x})(y_i - \bar{y})&=(0 - 2.5)(816-778.8)+(1 - 2.5)(802 - 778.8)+(2 - 2.5)(809-778.8)+(3 - 2.5)(780 - 778.8)+(4 - 2.5)(754-778.8)+(5 - 2.5)(712-778.8)\ &=(- 2.5)\times37.2+(-1.5)\times23.2+(-0.5)\times30.2 + 0.5\times1.2+1.5\times(-24.8)+2.5\times(-66.8)\ &=-93-34.8 - 15.1+0.6-37.2 - 167\ &=-346.5 \end{align*} ] [ \begin{align*} \sum_{i=1}^{6}(x_i-\bar{x})^2&=(0 - 2.5)^2+(1 - 2.5)^2+(2 - 2.5)^2+(3 - 2.5)^2+(4 - 2.5)^2+(5 - 2.5)^2\ &=6.25 + 2.25+0.25 + 0.25+2.25+6.25\ &=17.5 \end{align*} ] $m=\frac{-346.5}{17.5}\approx - 19.8$

Step3: Calculate the y - intercept $b$

Using the point - slope form $y=mx + b$ and the point $(\bar{x},\bar{y})$, we substitute $x = 2.5$, $y=778.8$ and $m=-19.8$ $778.8=-19.8\times2.5 + b$ $778.8=-49.5 + b$ $b=778.8 + 49.5=828.3$

The linear regression equation is $y=-19.8x + 828.3$

Step4: Estimate the year when $y = 604$

Set $y = 604$ in the equation $y=-19.8x + 828.3$ $604=-19.8x+828.3$ $19.8x=828.3 - 604$ $19.8x=224.3$ $x=\frac{224.3}{19.8}\approx11.3$

Since $x$ represents the number of years since 2013, the year is $2013+11.3\approx2024$

Answer:

The linear regression equation is $y=-19.8x + 828.3$. The calendar year is approximately 2024.