Bill Powers, age 16, of Rock Island, Ill., for his question:

WHEN DID MUHAMMAD ALI RETIRE FROM BOXING?

Muhammad Ali is the name of a boxer who was very popular for many years. His fame started when he won the light heavyweight boxing title in the 1960 Olympic Games. He retired in 1980.

Born Cassius Clay Jr. in Louisville, Ky., in 1942, he assumed the Muhammad Ali in 1967 after joining the Nation of Islam.

The fighter became world heavyweight champion when he upset Sonny Liston in 1964.

Ali refused to be inducted into the U.S. Army on the grounds that he was a minister and therefore a conscientious objector. He was subsequently convicted of draft evasion and the ruling bodies of boxing declared his title vacant.

Ali returned to the ring in 1970 and won two fights but lost a championship bout to Joe Frazier in 1971. Later that year the U.S. Supreme Court overturned his conviction.

Ali made a comeback in 1974 by defeating Frazier and, then, regained the heavyweight title by knocking out the champion, George Forman. Four years later, in 1978, he lost the title to Leon Spinks. But in the same year he regained the title by beating Spinks. Ali thus became the first heavy weight in history to win the championship three different times.

Ali first retired in 1979 but came out of retirement in 1980 to fight the new champion, Larry Holmes. Ali lost to the defender.