1. Suppose you are conducting a study of average lead in water in a region. Safe levels of lead must be less than 1 ppb (parts per billion). You want to determine if the average lead is considered "unsafe". You sample 15 homes and get a sample average of 2.14 ppb. The standard deviation of lead concentration is 0.8 ppb.
   1. Calculate the appropriate z- or t-statistic for this question. t= -5.43

X=1

N=15