The article "Influence of Penetration Rate on Penetrometer Resistance" (G. Gagnon and J. Doubrough, Canadian Journal of Civil Engineering, 2011: 741-750) describes a study in which 20 two-liter specimens of water were drawn from a public works building in Bridgewater, Nova Scotia. The mean lead concentration was \(6.7 \mu \mathrm{g} / \mathrm{L}\) with a standard deviation of \(3.9 \mu \mathrm{g} / \mathrm{L}\).

a. The Health Canada guideline states that the concentration should be less than \(10 \mu \mathrm{g} / \mathrm{L}\). Can you conclude that the water in this system meets the guideline?

b. A stricter guideline is being considered, which would require the concentration to be less than \(7.5 \mu \mathrm{g} / \mathrm{L}\). Can you conclude that the water in this system meets this guideline?