In a survey of forested watersheds in the congo, researchers chose 39 sites on first and second order streams and measured the following water qualitymetrics (NO_{3}^{-}, Total organic N, total NH_{3}-NH_{4}^{- }, DOC, SO_{4}^{2-}, Cl^{-}CA^{2+}, Mg^{2+}, H^{+}) as µmol l^{-1}. the table below summarizes some important statistics for two important ions, sulphate and chloride.

Attachment 29233

1. what probability distribution approximates the statistical distribution of sulphate in the rivers?

2. describe the distribution of chloride?

what is the best estimator of central tendency for sulphate?for chloride?

4. how many n is needed to estimate the sulphate concentrations in the watershed at a precision of 0.05?

5. how much n is needed to estimate the concentrations of chloride in the watershed at a precision of 0.05?

6. explain the principle why even the outliers, the sample mean for sulphate did not vary much even though highest standard concentration was included in the population.