In a study conducted by the Water Resources Center and analyzed by the Statistics Consulting Center at the Virginia Polytechnic Institute and State University, two different wastewater treatment plants are compared. Plant A is located where the median household income is below S22000 a year, and plant B is located where the median household income is above $60000 a year. The amount of wastewater treated at, each plant (thousand gallons/day) was randomly sampled for 10 days. The data are as follows:
Plant A: 21 19 20 23 22 28 32 19 13 18
Plant B: 20 39 24 33 30 28 30 22 33 24
Can we conclude, at the 5% level of significance, that the average amount of wastewater treated at the high income neighborhood is more than that from the low income area? Assume normality.