SQL Acosta Rodriguez Luis

select materia, count(*)/(select count(*) from financiera) as probabilidad from financiera where materia in(select distinct materia from financiera)  group by materia;  

select materia, industria, count(*)/(select count(*) from financiera) as Probabilidad from financiera where materia in(select distinct materia from financiera)  and industria in(select distinct industria from financiera) group by industria, materia order by materia, industria;
true.