Research (June 1995) published a study of the mating systems of hermaphroditic snail species. The mating habits of the snails were classified into two groups: (1) self-fertilizing (selfing) snails that mate with snails of the same sex and (2) cross-fertilizing (outcrossing) snails that mate with snails of the opposite sex. One variable of interest in the study was the effective population size of the snail species. The means and standard deviations of the effective population size for independent random samples of 17 outcrossing snail species and 5 selfing snail species are given in the accompanying table.

	Effective Population Size
Snail Mating System	Sample size	Mean	Standard deviation
Outcrossing	17	4894	1932
Selfing	5	4133	1890

a) Compare the mean effective population sizes of the two types of snail species with a 90% confidence interval. Interpret the result. b) Geneticists are often more interested in comparing the variation in population size of the two types of mating systems. Conduct this analysis for the researcher and interpret the result completely.