Question: A certain enzyme in fish liver is considered an indicator of a certain harmful pollutant. When the enzyme activity falls below 50 units/gm liver, the pollutant is considered to be present at harmful levels. The following random sample was taken from the lake in question and enzyme activity measured.

48 43 51 42

50 42 44 45

56 49 44 47

50 49 38 46

38 52 32 56

Is there evidence that the water is polluted?