Rhonda Hill, a black Fairfax County school teacher who lives in Alexandria, was appointed the newest member of Alexandria School Board last night, bringing the number of blacks on the nine-member body to three.

At the same time, the City Council reappointed Mary Jane Nugent and Board Chairman Lou B. Cook to three-year terms. Cook and Nugent got five votes each on the council's first ballot, while Hill tied with the only other black among the 12 candidates, attorney A. Melvin Miller. In a run-off vote, Hill won with four votes to Miller's three.

"I'm elated, ecstatic, thrilled," Hill said shortly after the vote. "Now I'm going to work to make this the best school system ever."

Hill said she will work to ensure that all children receive a quality education in the city's public schools, whose enrollment is almost 50 percent black.

Some council members said they felt pressure from the community and from other council members to appoint another black board member. The board has been criticized as failing to be representative.

Monday night, while being interviewed by the council, Hill criticized what she said is a tendency of educators today to discourage low-income students from preparing for college. She said that because a student's family cannot afford to send their child to college is no reason to force a student into vocational and work world training.

Hill teaches job development for learning-disabled students.

Hazel Rigby, president of the Education Association of Alexandria, praised the council's selections, calling Hill's appointment "terrific."

"She's an educator," Rigby said, "and she seems very concerned about education, teachers and students. I think that's refreshing."

The council's lone black member supported Miller and in remarks following his vote, explained that he believed Miller was more qualified than Hill. Republican council members Carlyle C. Ring, Jr. and Margaret B. Inman also supported Miller.

In other action last night, the council voted against considering a proposal to build a multimillion-dollar stadium for the Alexandria Dukes professional baseball team. "Our future will probably be in another county in Northern Virginia," said Eugene Thomas, president of the Dukes. "I don't foresee staying in Alexandria for one more year."