Answer:
Null hypothesis: There is no statistically significant difference between our expected and observed values.
Degree of freedom: 1
Chi squared: 1.333
Null hypothesis is supported since our chi squared value is lower than our critical value, there are no statistically significant difference
Explanation:
The Null hypothesis is a hypothesis that stipulates that there is no difference between the population being compared during statistical analyses/tests. Hence, in this case, the Null hypothesis posits that there is no significant difference between the expected and the observed phenotypic ratio.
Degree of freedom is calculated as n-1, where n = number of phenotypes in this case. Hence, Degree of freedom = 2 - 1 which is equal to 1.
Chi square ([tex]X^{2}[/tex]) = [tex](Observed frequency - Expected frequency)^{2}/Expected frequency[/tex]
Since purple is dominant over white, the phenotype of the offspring should be 3:1 purple:white according to law of segregation. Hence, since there are 100 offspring in total;
Expected frequencies: purple 75, white 25
Observed frequencies: purple 70, white 30
([tex]X^{2}[/tex]) white = [tex](30-25)^{2}/25[/tex] = 1
([tex]X^{2}[/tex]) purple = [tex](70-75)^{2}/75[/tex] = 0.33
Hence, total ([tex]X^{2}[/tex]) = 1.33
The decision rule is such that;
In this case, the calculated ([tex]X^{2}[/tex]) value is 1.33 and the critical value is 3.841, hence calculated value is less than the critical value. The Null hypothesis is supported.
