The results of an evaluation of the drinking water quality in Pakistan was reported in Drinking Water Engineering and Science (Vol. 6, 2013). Due to high levels of fluoride in the drinking water, Pakistanis are susceptible to fluoride toxicity (fluorosis)—which occurs when the fluoride level exceeds 1.5 milligrams per liter of water (mg/l). Water specimens were collected from various surface or groundwater sources (e.g., hand pumps, wells, springs, dams, etc.) of major cities of the country. The table gives the results for two cities—Lahore and Faisalabad. Is there evidence to indicate that the fraction of water specimens that exceed 1.5 mg/l of fluoride differs for the two cities? Test using α = .10.

Transcribed Image Text:

Lahore Faisalabad Number of water specimens sampled 79 30 Number exceeding 1.5 mg/l of fluoride 21 4