Genetic Variation in Fast-Twitch Muscles Chi-square tests are common in genetics. A gene called ACTN3 encodes a protein which functions in fast-twitch muscles. People have different variants of this gene, classified as RR, RX, or XX. Computer output is shown for testing whether the proportions in these categories are 0.25, 0.5, and 0.25, respectively. The observed counts come from a study conducted in Australia Chi-Square Goodness-of-Fit Test for Observed Counts Test Contribution Category Observed Proportion Expected to Chi-5q RR 130 0.25 109 4.04587 RX 226 0.50 218 0.29358 XX 80 0.25 109 7.71560 N DE Chi-5q P-value 436 2 12.0550 0.002 (a) What is the sample size? i (b) What is the observed number of people with the variant AR for this gene? What is the expected number of people in this group under Ho? Observed = Expected = 1 (c) Which variant contributes the most to the chi-square statistic? XX For this variant, is the observed value greater than or less than expected? Less than (d) What are the degrees of freedom for the test? Degree of Freedom = i (e) What is the p-value? p-value = i Do the assumed proportions appear to be accurate? No