1. The problem statement, all variables and given/known data Q1) It has been observed that contamination level of water [measured in suitable units] in a given waterbody has lognormal distribution with mean = 23.58 units and variance = 3.85 sq units. What % of samples would indicate contamination level between 20.65 units and 25.85 units ? 2. Relevant equations Using the Z table and P((ln(x)-mean)/SD) 3. The attempt at a solution P((ln(20.65)-23.58)/sqrt(3.85))<=Z<=((ln(20.65)-23.58)/sqrt(3.85)) = phi(-10.36)-phi(-10.47) Values are way too large... whats going on.