The scores of Prince George's County high school students on standard college entrance examinations dropped last year in both verbal and mathematical aptitude and remained significantly lower than the average scores of students both in Maryland and nationwide, school officials said yesterday.

Although the average national and state scores on the Scholastic Aptitude Tests (SAT) for high school seniors remained constant on the state and national level for verbal aptitude and rose slightly in math, Prince George's students' average scores dropped seven points in verbal and four points in math.

School officials maintained yesterday the the lower scores of county students could be attributed, in part, to the fact that a higher percentage of students in the middle and lower ranks of Prince George's schools took the tests than on the state or national level. They pointed out that the scores of county students in the top 10th of their classes compared favorably with similar students across the country.

School Board President Norman Saunders was more concerned. "This just shows more than ever before that we need to reinforce the basics in the schools, and that we need to locate whatever difficulties are causing lower scores," he said.

The 3,483 high school seniors who took the SAT's in Prince George's last school year averaged 409 points of a possible 800 on the verbal section, and 453 of 800 in math. The lowest Possible score is 200.

In comparison, students in Maryland as a whole average 431 on verbal and 466 on math, and the national average was 429 verbal and 468 math.

While the average scores of Maryland students have dropped about five points in verbal and math the past three years, Prince George's verbal average has declined nine points from 418, and even more rapidly in math, according to Dr.Harry Gemberling, a school research and evaluation specialist.

"I couldn't account for that except to say the ability of students might be dropping," Gemberling said. "But there's no way to measure a drop in ability."

Gemberling argued that the county's lower scores did not necessarily mean that Prince George's students were failing to perform aswell as students in the state or the nation.

He pointed out that while22 percent of the students who take the SAT's nationally are ranked in the top 10th of their high school classes, only 16 percent of the Prince George's students who take SAT's have class ranks in the top 10 percent. "So, the two samples are self-selecting and not necessarily comparable," he said.

The scores of county students in the top 10th of their classes were higher than their counterparts in both Maryland and the nation in nathematics, and were above the national average for high-ranked students in verbal aptitude.

In addition, students in Prince George's outscored students in both the state and the nation on the College Board Achievement tests. The achievement tests, which measure mastery of subject content rather than aptitude, are normally taken by students with strong academic records, Gemberling said.