9.
某种产品的广告费支出\(x\)与销售额\(y\)\((\)单位:百万元\()\)之间有如下对应数据:
\(x\) | \(2\) | \(4\) | \(5\) | \(6\) | \(8\) |
\(y\) | \(30\) | \(40\) | \(60\) | \(50\) | \(70\) |
\((1)\)判断变量\(x\)与\(y\)之间是否具有相关关系?如有,是正相关还是负相关?
\((2)\)求线性回归方程; \((3)\)试预测广告费支出为\(10\)百万元时,销售额多大?
\((\)回归方程为\( \overset{\}{y}= \overset{\}{b}+ \overset{\}{a} \),\( \overset{\}{b}= \dfrac{ \sum\limits_{i=1}^{n}{x}_{i}{y}_{i}−n \overset{¯}{x} \overset{¯}{y}}{ \sum\limits_{i=1}^{n}x_{i}^{2}−n{ \overset{¯}{x}}^{2}} \),\( \overset{\}{a}= \bar{y}- \overset{\}{b} \overset{¯}{x} )\)