Investigation: Filtering Water in Cameroon Students and professors in the Nursing and Engineering Departments at Hope College went to the central African country of Camcroon to help improve drinking water quality and community hcalth in rural communities by intalling water filters in or near homes in one village. The families living in this village had no electricity, had no water distribution system, and got their water from streams. The filters they installed contained a diffuser plate, fine sand, coarse sand, and gravel. Using the new filters, family members were expected to gather their water and filter it before drinking, instead of drinking directly from the stream as was common practice. Students working on this project examined the quality of the filters by looking at many different variables, including general observations, filter observations, microbiology observations, household practice observations, user perceptions, and water source observations. It should be noted, when making inferences, the water filters in this data set should be treated as a sample of all filters that could be constructed if this pilot project were expanded to other villages. Thus, inference is to an as-yet-unbuilt, larger population of filters. Step 1: Ask a research question. There are several rescarch questions we will ask in this investigation. The first one is: On average, is there a significant difference in the E. coli counts between the water that has just been filtered and water that is sitting in the bottom of a filter after it was filtered the previous day? The data set we will use contains results from 14 water filters each giving E. coli counts (per 100 mL) on the first day and the second day after the water was filtered. Step 2: Design a study and collect data. 1. Identify the observational unit. Select one. A. Students B. Filters C. Residents D. Water 2. [2 pts Select one answer within each bracket to complete the description of each variable listed explanatory variable and it is quantitative E. coli count is the