Because a total of 83 progeny were produced in the testcrosses, we expect 1/4 X 83 = 20.75 of each. The observed numbers of progeny from the testcross (30, 10, 12, 31) do not appear to fit the expected numbers (20.75, 20.75, 20.75, 20.75) well; so independent assortment may not have occurred.
To test the hypothesis, carry out a series of three chi-square tests. First, look at each locus separately and determine if the observed numbers fit those expected from the testcross. For the locus determining coat color, crossing Ww X ww is expected to produce / Ww (black) and / ww (white) progeny, or 41.5 of a total of 83 progeny. Ignoring the hair type, we find that 30 + 10 = 40 black progeny and 12 + 31 = 43 white progeny were observed. Thus, the observed and expected values for this chi-square test are:
Phenotype Observed black 40
The chi-square value is:
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