You are referring to the possessive, not the plural.
A singular noun ending in a consonant and then y makes the plural by dropping the y and adding-ies.
Note that some dictionaries list "busses" as an acceptable plural for "bus." Presumably, this is because the plural "buses" looks like it ought to rhyme with the plural of "fuse," which is "fuses." "Buses" is still listed as the preferable plural form. "Busses" is the plural, of course, for "buss," a seldom used word for "kiss."
Fractions with numerators larger than one can be handled both ways. This also applies to percentages. The plural form is used for countable objects, and the singular form is used for non-countable objects. See
The plural form of most nouns is created simply by adding the letter
M.G..Smith wrote originally about Grenada but his theory of the plural society has been widely used in the analysis of colonial and post-colonial societies in the Caribbean. Smith is aware of the general sociological theory of Talcott Parsons and its assumption of four mutually supportive institutions. In the Caribbean, however he argues that there are several co-existing ethnic groups each of which has a nearly complete set of social institutions. Setting his argument within the context of a review of social anthropological theories used in studying the Caribbean, he sees the various ethnic groups as having their own family systems, there own productive economies, their own languages and religion but not their own political system. In the political sphere they are all controlled by one dominant segment... To put this in more concrete terms Blacks are descended from Slaves, Indians from indentured labourers. The groups have remained distinct and have their own institutions. They exist however politically under the domination of an outside power. Thus the defining feature of a plural society is seen as this process of the domination of all ethnic groups by the colonial power. New problems arise when the colonial power withdraws.Rex has attempted to set out a theory of the plural society which does justice to Marxian and other theories as well as those of Smith. This involves first of all recognizing that such societies go though several phases of development, pre-colonial, colonial and post colonial. In the colonial phase relations to the means of production are important, even though they are more varied than Marxist categories suggest involving such structures as the encomienda in Spanish America. At the same time however groups have a relationship to each other reminiscent of the mediaeval estate system in Europe different groups having the cultures, rights and privileges which attach to their function. In the post-colonial phase there would be according to this theory a number of developments. One would be the subordination of peasants to the large estates or latitudinal, a second would be the replacement of the former colonial power by a group able to take over its powers, a third would be a change in which new primarily economic centres replaced the colonial power, and so far as resistance and struggle within the new system is concerned.