The article "The Statistics of Phytotoxic Air Pollutants" (J. of Royal Stat. Soc., 1989: 183-198) suggests the lognormal distribution as a model for SO2 concentration above a certain forest. Suppose the parameter values are µ = 1.9 and σ = .9.
a. What are the mean value and standard deviation of concentration?
b. What is the probability that concentration is at most 10? Between 5 and 10?