Two out of three Montgomery County black ninth graders and more than one out of two Hispanic students failed last fall's state math competency exam, a showing far worse than white students, school officials said yesterday.

Superintendent Edward Andrews, in a 15-page analysis, said yesterday that the performance of county black and Hispanic students was the most disturbing aspect of the already troubling results of the state-mandated exam by Montgomery County students and was one that required immediate attention.

School and community leaders reacted with shock last month when officials announced that 35 percent of all county ninth graders had failed the exam. But yesterday, after the scores were broken down by race, black and Hispanic leaders questioned whether the results indicated the school system had a double standard for educating children of different races. Only 34 percent of black ninth graders and 42 percent of Hispanic students passed the exam, which measures students' ability to perform simple mathematical computations. Seventy percent of the white students and 77 percent of the Asian students passed the exam.

Beginning in 1987, students must pass the exam to graduate from high school.

"The disproportionate number of minority students who failed again reinforces the belief that many of us in the Hispanic and other minority communities have that our youngsters are not afforded the types of equal educational opportunities that will allow them to grow into the types of jobs that are more commensurate with their intellectual skills and capacities," said Ileana Herrell, the county's Hispanic affairs adviser.

In his report yesterday, Andrews said he did not know what caused the poor showing by Hispanic and black students, but he noted that the majority of these students were enrolled in less advanced junior high and high school math classes.

This disproportionate representation should be corrected immediately, Andrews said.

Of the five math courses typically taken by ninth-grade students fewer than 10 black or 10 Hispanic students had enrolled in the most difficult course in which 241 ninth graders were enrolled, according to school records. More than 60 percent of the black students and more than half the Hispanic students had enrolled in what are considered the two lowest-level math classes. Blacks represent 12.4 percent of the county's ninth graders. Hispanics represent 4.7 percent.

"But if black students are not taught, how can you expect them to perform?" asked Eula Odom, education chairman of the county's NAACP chapter. "Black children in Montgomery County are systematically discouraged from taking the more difficult math courses that would prepare them for these kinds of tests."

State officials and officials in some other jurisdictions said yesterday that they did not intend to produce a breakdown of student performance along racial lines. Throughout the state, 60 percent of all ninth graders failed the proficiency test.

Montgomery County officials yesterday, however, questioned the state's unwillingness to collect the data and said that the discrepancy between races was high enough to warrant a careful look at the problem.

In addition to his comments about minority performance, Andrews also outlined numerous steps the school system would take as a result of the math scores.

Included among them are: testing at the end of the year in the fourth through eighth grades to measure student progress; math preparation as early as kindergarten; daily testing in the seventh grade of skills needed to pass the exam and review of new ways to improve the quality of math instruction by trying different teaching methods.