Montgomery County ninth graders posted overall higher scores on the state's functional math and reading tests this year, but the percentage of Hispanic students passing the tests declined and black students still trail whites, county school officials reported yesterday.

School Superintendent Wilmer S. Cody said he was disturbed by the test results of Hispanic students, which school officials said may be caused in part by language difficulties.

This year, 83 percent of all Montgomery County's ninth graders passed the state's functional math test, an increase of 4 percent over last year, and 96 percent of the ninth graders passed the functional reading test.

The rate of Hispanics who passed the math test was 63 percent this year, compared with 66 percent last year, while 86 percent passed the reading test, compared with 92 percent last year.

School spokesman Sally Keller said those declines could probably be attributed to "a language barrier." For the last five years, the county's schools have been feeling the impact of a steady stream of illiterate or barely literate refugee children from Central America, according to school officials.

This theory is supported, school officials said, by statistics that indicate that the fewer the number of years students have been in Montgomery County schools, the lower the percentage that passes the test.

Fewer than 60 percent of Hispanics who have been in Montgomery County schools for one year passed the math test, compared to almost 90 percent among those who have been there five years.

Asian-Americans scored lower than whites in reading, but, as they have done in the past, higher than whites in mathematics.

While school officials said they were pleased with the overall scores, and both whites and blacks posted gains in their math scores over last year, black students still trailed white students by 23 percentage points on the math test.

Sixty-five percent of the county's black ninth graders passed the test, an 8 percent improvement over the previous year, while 88 percent of white students passed the math test, an increase of 6 percent.

On the reading test, blacks trailed whites by just 3 percentage points, with 96 percent of black ninth graders passing, compared with 99 percent of white ninth graders.

The county has about 94,000 public school students, about 14 percent of them black and 8 percent Hispanic.

This year's 12th graders must pass the reading test to graduate. The math test and a writing test become graduation requirements for next year's seniors.