"composed a majority" is correct and usable in written English.
You can use it when referring to a group of people or things that form the majority of a larger group. For example, "The graduating class composed a majority of students from the school's honors program."
Together, these Justices composed a majority of the quorum of six Justices who participated in the case.
Several towns have apparently been won by parties representing refugees who once composed a majority of the residents but were driven out in ethnic cleansing.
If Republicans hadn't stubbornly blocked then president Barack Obama's 2016 nomination of Merrick Garland to the Supreme Court, justices appointed by Democrats would have composed a majority on the nation's highest court for the first time since 1970.
Women compose a majority of the American population but continue to be underrepresented in government, elected office, the courts and business world.
If King Hussein is truly interested in Middle East peace, perhaps he should give back his "kingdom" to the Palestinians who compose a majority of the population.
But it has been unable to significantly reduce the population of families with children, who compose a majority of the shelter population.
You can't do that with a group of citizens that are going to compose a majority of this state by 2020, and which will be a plurality of this state in about a year and a half".
There's a wide range of black holes that we know of, but also a wide range of studies that rule out black holes composing a majority of the dark matter over a huge variety of regimes.
Ward's hierarchical clustering applied to these immune modules separated C2 and C3 patients into two clusters: one exclusively composed of C3 patients with HIR (n = 26) and the other composed of a majority (84%) of C2 patients with low immune response (LIR).
