Disasters (Vol. 28, 2004) published a study of the effects of a tropical cyclone on the quality of drinking water on a remote Pacific island. Water samples (size 500 milliliters) were collected approximately four weeks after Cyclone Ami hit the island. The following variables were recorded for each water sample: a. Town where sample was collected b. Type of water supply (river intake, stream, or borehole) c. Acidic level (pH scale, 1 to 14) d. Turbidity level (nephalometric turbidity units NTUs) e. Temperature (degrees centigrade) f. Number of fecal coliforms per 100 milliliters g. Free-chlorine residual (milligrams per liter) h. Presence of hydrogen sulphide (yes or no) Identify each variable as quantitative or qualitative.

A quantitative variable is the one that can be measured numerically (in a discreet form or a function form). A qualitative variable are those that can´t be a numerical value but can be organized in groups.

Assuming these statements, we can determine that the variables in a), b) and h) are qualitative, while the variables in c), d), e), f) and g) are quantitative ones.

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