: 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.
However, the SSA looks at how much you earned in a year and divides that figure by the minimum amount required to earn credit for a quarter. Thus, if you earn at least $4,800 in January and February of 2015 and don't work the rest of the year, you will receive credit for four quarters of work ($4,880/$1,220 = 4).