Black students scored an average of 110 points lower than their white classmates on last year's college entrance exams, with the lowest scores being tallied by students whose parents had the least income and education, according to figures released by the College Board.

In the first analysis ever published of how various racial groups fared on the Scholastic Aptitude Test (SAT), the board found that students from affluent black and white families scored considerably higher on the tests than did low-income students. The figures also show that fewer blacks than whites were enrolled in college preparatory programs.

George H. Hanford, president of the New York-based group of colleges and education associations, said that while the board has been collecting such data since 1971, it decided to publish the racial figures this year "to illuminate the extent and nature of the educational deficit this nation must overcome."

Hanford cautioned that the figures "lend themselves to misrepresentations by those who seek simple explanations," and he said the average scores should not "obscure the fact that a significant number of minority youth score well on the SAT."

On the verbal portion of last year's SAT, where scores range from 200 to 800, the median score for white high school students was 442. By contrast, the median score was 391 for American Indians, 373 for Mexican-Americans, 361 for Puerto Ricans and 332 for blacks.

The gap was greater on the mathematics portion of the test, where the median score was 483 for whites and 362 for blacks.

These figures were gathered from about 90 percent of the 1 million high school students who took the SAT last year and voluntarily filled out questionnaires about their race, income, education and family background.

Some analysts said the disparities in the SAT scores between whites and blacks were caused by wide differences in family income, home environments and educational opportunities.

"The tests are simply a reflection of the educational advantages that wealthy kids have," said Dr. Lloyd Bond, associate professor of psychology at the University of Pittsburgh. "I'd be suspicious if the tests didn't show these differences between wealthy and poorer kids. The quality of instruction is vastly superior in suburban schools as opposed to inner-city schools."

Among black students, for example, 17.5 percent reported that their parents made less than $6,000, and these students had a median score on the verbal test of 284. But for the 1.8 percent of blacks from families earning more than $50,000, that figure rose to 414.

Only 2.2 percent of white students said their families earned less than $6,000, and their median verbal score was 404, compared to 461 for the 12.8 percent from families earning more than $50,000.

Parental education was also a factor. About 60 percent of the black students said their fathers had a high school diploma or less, about twice the proportion found among their white classmates. Conversely, 8.4 of the blacks said their fathers had a graduate or professional degree, compared to 21.7 percent of the whites. Such differences correlate with a swing of 75 to 100 points among both races.

The impact of family background on test scores also was apparent in looking at other ethnic groups.

Half the Puerto Rican students, who scored just ahead of blacks on the SAT, came from families earning less than $12,000, and nearly one in five had fathers who had finished only grade school.

But 43 percent of Asian-Americans, who as a group outranked even white students with a median math score of 513, came from families earning more than $24,000, while nearly a quarter had fathers with graduate or professional degrees.

"As young children, the poorer students are not getting as stimulating an environment as more educated parents are apt to provide," said Ann Cleary, director of evaluation services at the University of Iowa. "And more of the black youngsters are living in single-parent homes, where they may not be getting as much attention."

As for criticism that the tests are culturally biased against certain groups, Cleary said: "The tests don't measure everything a youngster knows, but they do predict how well people will do in college."

She said that more pre-school programs and remedial courses could help disadvantaged students close the gap, "which is easier when the child is 5 years old than when he's 18."

The board found that 61.8 percent of the black students and 78.9 percent of the whites were enrolled in academic or college preparatory programs, and that both groups scored better than those taking general or career-oriented courses. Cleary also noted that white students reported taking more math, physical science and foreign language courses.

The College Board reported two weeks ago that overall SAT scores rose slightly this year, reversing an 18-year decline.