The article “A Probabilistic Analysis of Dissolved Oxygen–Biochemical Oxygen Demand Relationship in Streams” (J. Water Resources Control Fed., 1969: 73–90)

reports data on the rate of oxygenation in streams at 20°C in a certain region. The sample mean and standard deviation were computed as and , respectively. Based on the accompanying frequency distribution, can it be concluded that oxygenation rate is a normally distributed variable? Use the chi-squared test with

.

Rate (per day) Frequency Below .100 12

.100–below .150 20

.150–below .200 23

.200–below .250 15

.250 or more 13