: 11 The later definition by Cavalli-Sforza & Bodmer (1971) is currently used: Genetic polymorphism is the occurrence in the same population of two or more alleles at one locus, each with appreciable frequency, where the minimum frequency is typically taken as 1%.
The financial world splits up its calendar into four quarters, each three months long. If January to March is the first quarter, April to June is the second quarter, and so on, though a company's first quarter does not have to begin in January.
A quarter system divides the academic year into four terms, one per season, with attendance required in three quarters per year to total 32 to 36 weeks of instruction. A semester system divides the academic year into two terms of equal length, with attendance required in both semesters to total 32 to 36 weeks of instruction.