ABC corporation periodically runs consumer satisfaction tests for its two retail outlets in a city.

The company wants to test whether the consumers are equally satisfied with the service

provided at these two locations. A Sample of 380 customers selected from location I produced a

mean satisfaction index of 7.6 on a scale of 1 to 10 (1 being the lowest and 10 being the highest)

with a standard deviation of .75. Another sample of 370 customers selected from location II

produced a mean satisfaction index of 8.1 with a standard deviation of .59. Assume that the

customer satisfaction index for each location has unknown but equal population variance.

a) Construct a 98% confidence interval for the difference between the mean satisfaction

indexes for all customers for the two locations.

b) Test at 1 percent level of significance whether the mean satisfaction level for all customers

in the two locations are different.