



 
Hi Adrian. "Assume the distribution of wages is normal" means that it follows a normal distribution curve (this used to be called a bell curve because of its shape). This is a very welldefined curve that has some specific properties relating to area. The percentages are the proportion of the area under each portion of the curve compared to the area under the entire curve. This means that the entire group of salaries is the area under the curve, the 0 point is the mean salary and σ is the standard deviation. Here's an example I'll solve:
Hope this helps you with your problem,  


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences. 