The Post's coverage of the Maryland State Writing Exam {Metro, May 9} left me feeling not only disappointed, but also angry. Statistics don't lie but they can certainly be used to mislead.

As a proud resident of Prince George's County, I am tired of playing "second fiddle" to the Montgomery County school system. In this situation I am especially frustrated because it turns out that our scores, when computed in a similar fashion, are the top in the state, surpassing even Montgomery County's.

I fail to understand why the chart citing the various passage rates for the exam did not either limit itself to the state department figures or wait until revised figures were available from the other jurisdictions. In spite of the asterisks at the bottom of the chart, the chart was still subject to misinterpretation. It would have been easy to conclude that Montgomery County has a special population of students with severe handicaps that other counties do not have. It does not indicate that revised figures exist for all the counties mentioned.

Second, while rightly being encouraged by the increased passing rate for minority students, why limit the comments to Montgomery County? Devoting two entire paragraphs solely to Montgomery County was galling for an article that claimed to be about Maryland, not a promo for the Montgomery County school system.

It is ultimately this second area that is of most concern to me. Prince George's school system has committed itself to make learning work for all of our students. Even given the data used for the article, Prince George's County had the highest passing rate for black and Hispanic students. It was most disturbing that there was no mention of this in the article. ALICE E. PETILLO Lanham