In April 2014, the city of Flint, Michigan stopped buying water that came from Lake Huron and started using water from the Flint River to save money. After the move, residents of Flint started experiencing symptoms that could be attributed to the consumption of lead. Open the data file3_5_17 at www.pearsonhighered.com/sullivanstats.
(a) Draw a boxplot of Lead (ppb), which represents the lead content in parts per billion of a sample of 71 properties in Flint, Michigan between February and June 2015.
(b) The Lead and Copper Rule of 1991 states that if more than 10% of homes have lead readings greater than 15 ppb, then action must be taken to reduce lead readings in the water. What percent of the properties had a lead reading greater than 15 ppb?
(c) After considering the data, Flint officials excluded the home at 212 Browning Avenue because it had a water filtration system and excluded the property at 625 S. Grand Traverse because it was a business (not a residential property). Draw a boxplot of the data with these properties removed.
(d) In the data set with these properties removed, what percent of the homes had a lead reading greater than 15 ppb?
(e) Discuss the impact of removing outliers from data sets as it pertains to the Flint water crisis.