A real estate development corporation wants to demolish an abandoned factory and build condominiums in its place. Before proceeding with this plan, the corporation tests the site for toxic contaminants. Fifty core samples are randomly collected from various locations around the site and analyzed for cadmium (Cd). If the average concentration of cadmium in the soil is 0.8 mg/kg or higher, the site is declared contaminated and the developer will scrap its plans because the project will be too costly, The results of the sampling are shown in the table at right.

a. How many samples are contaminated?
b. Find the mean and standard deviation of these data.
c. If the true concentration of cadmium in the soil is
0.8 mg/kg, what is the probability of these results?
d. Will the developer build the condominiums?

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Concentration of Cd (mg/kg) 0.89 0.4 0.56 0.29 0.51 0.30 0.53 0.71 0.79 0.61 0.77 0.36 0.24 | 0.62 0.55 0.63 0.40 0.43 0.63 0.89 047 0.33 0.32 0.22 0.71 0.57 0.500.98 0.66 0.72 0.43 0.54 0.65 0.95 0.11 0.78 0.75 0.45 0.69 0.77 0.62 0.88 0.36 0.71 0.58 0.36 0.61 0.370.39 0.53