A certain type of plant produces red flowers if it is homozygous for the "red" allele and white flowers if it is homozygous for the "white" allele. Due to incomplete dominance, heterozygous plants (those with one "red" and one "white" allele) produce pink flowers. When two plants that produce pink flowers are crossed, they should produce red:pink:white flowering offspring in the ratio of 1:2:1. Suppose that 200 offspring were planted. Red flowers were produced by 42 plants, white flowers by 47 plants, and the rest were pink. Perform a chi-square goodness-of-fit test at the 5% level of significance to see if these values fit the hypothetical 1:2:1 Mendelian ratio.
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The expected frequencies of red, pink and white are 200/4 = 50, 200*2/4 = 100 and 200/4 = 50 respectively. The observed value of the chi-square test statistic is
Sum[(Oi-Ei)^2/Ei] = (42-50)^2/50 + (111-100)^2/100 + (47-50)^2/50 = 2.67
The 5% critical value for Chi-square test for 2 df is 5.99.
Since, observed value 2.67 is below 5.99, we fail to reject Ho.
Sum[(Oi-Ei)^2/Ei] = (42-50)^2/50 + (111-100)^2/100 + (47-50)^2/50 = 2.67
The 5% critical value for Chi-square test for 2 df is 5.99.
Since, observed value 2.67 is below 5.99, we fail to reject Ho.