parameterization

So, a colleague of mine, who is a survey methodologist, is proposing to do an experiment on a survey. * The purpose of the experiment is to see if the communication protocol for the survey has impacts on (1) response rates, and (2) if specific protocols have higher acceptance rates by people...

I'm a little stuck, and hope someone will be able to explain this to me. I have sample mean, and value of the 90th percentile of the sample. If distribution is assumed to be LogNormal, is there a way of estimating parameters of mu and sigma of that LogNormal distribution? I'm trying to...