Alumni Clubs
Three Alumni Clubs for a University Have Members

Alumni clubs
Three alumni clubs for a university have members who contribute to the university athletic program.The amount of contribution (in dollars)for six contributors randomly selected from each city to test the hypothesis that the mean contribution is the same among alumni clubs is given below,followed by the total for each city: $$\begin{array} { | l | l | l | } \hline { \text { Banks } } & { \text { Business Services } } & { \text { Construction } } \\\hline n _ { 1 } = 7 & n _ { 2 } = 7 & n _ { 3 } = 7 \\\bar { x } _ { 1 } = 41 & \bar { x } _ { 2 } = 30 & \bar { x } _ { 3 } = 24 \\\sum _ { i = 1 } ^ { n _ { 1 } } \left( x _ { 1 } - \bar { x } _ { 1 } \right) ^ { 2 } = 882 & \sum _ { i = 1 } ^ { n _ { 2 } } \left( x _ { i 2 } - \bar { x } _ { 2 } \right) ^ { 2 } = 1266 & \sum _ { i = 1 } ^ { n _ { 1 } } \left( x _ { i 3 } - \bar { x } _ { 3 } \right) ^ { 2 } = 582 \\\hline\end{array}$$
-What is the number of the error degrees of freedom?