The residents of Georges Plain complain that the local government charges for the removal of additional household rubbish in their community are higher than those charged in Burnt Savannah. Georges Plain council’s refuse manager has agreed to study the problem and to indicate the complaints were reasonable. Independent random samples of the amounts paid by residents for household waste removal in each of the two communities over the last three months were obtained. These amounts were as follows:

Question

The residents of Georges Plain complain that the local government charges for the removal of additional household rubbish in their community are higher than those charged in Burnt Savannah.  Georges Plain council’s refuse manager has agreed to study the problem and to indicate the complaints were reasonable.  Independent random samples of the amounts paid by residents for household waste removal in each of the two communities over the last three months were obtained.  These amounts were as follows:

anonymous · Answer

Georges Plain  142  140  142  100  125  135  128  128  137  156
Burnt Savannah   75  87  95  100  95  105  85  110
Assume equal population variances, find a 80% confidence interval for the difference in the mean costs for the removal of additional household rubbish in the two communities.