Problem 4. Water quality measurements taken daily from a river show the following concentrations (in milligrams per liter) of chlorides (C) and phosphates (P) over a 30-day period: C Р C Р C P C P C P 60.1 1.31 63.9 1.97 69.1 1.92 66.0 1.86 65.0 2.07 61.5 1.39 65.1 1.99 68.0 2.00 66.1 1.65 69.1 1.58 64.1 1.59 64.9 1.98 68.1 1.90 65.0 1.58 65.0 1.93 62.9 1.68 67.1 2.15 68.9 1.74 64.0 1.74 61.1 1.72 65.0 1.89 69.9 2.12 63.0 1.81 63.1 1.89 62.0 1.73 64.2 1.98 72.5 2.15 68.1 1.86 65.9 1.94 62.1 1.82 a) Plot a histogram, a normalized frequency diagram and a cumulative frequency diagram of the daily concentrations of phosphates. b) Estimate the sample means, standard deviations, and coefficients of variation for the two types of measurement. Comment on the relative variation in each measurement. c) Plot a scatter diagram for the above data and estimate the sample correlation coeffi- cient. Do you see any relation between the daily measurements of chlorides and phos- phates?