In a certain Midwestern community, 25% of the population consists of third generation descendants of one Finnish immigrant family. Within the community there is a remittent nervous disorder that may be transmitted genetically. There are 75 cases of the disorder on which to base studies.

a. If the disorder is not genetic or in any way associated with ethnic origin, what percentage of those with the disorder are likely to be third-generation descendants of that family?

b. What are the most logical null and alternative hypotheses to test whether the disorder is genetically controlled?

c. If 28 of the 75 cases are third-generation descendants of the Finnish family, carry out the test at the 0.05 level of significance.