Q:

Find mean from 5th percentile

I need some guideance with a statistics problem. I have a situation where a know the 5th percentile of a normal distributed continous random variable. I want to compute the average value. The data set and standard deviation are not known. 
I want to solve my problem with R, do you have any hints for useful functions or methods?
Thanks, John

A:

Normal distribution is described by mean and deviation (two values), and you know 5th percentile only (one value). It's necessary to have some additional value (e.g. 10th percentile) to calculate mean and deviation.

