Are my answers here correct ?

Research questions for z test, t test for independent samples and t test for dependent samples :

z test: "An investigator is interested in finding out whether the particular sample of college students is similar to or different from college students in general.

t test for independent samples: "Do 11th graders have significantly more unexcused absences than 10th graders in junior highs?

t test for dependent samples: " Do people drop weight after attending a weight loss boot camp for 2 months?

Yes, your answers are correct.

For the z test, it is used when comparing a sample to a population to determine if they are similar or different.

For the t test for independent samples, it is used to compare the means of two independent groups (in this case, 11th graders and 10th graders) to determine if there is a significant difference in the variable of interest (unexcused absences).

For the t test for dependent samples, it is used to compare the means of the same group before and after a treatment or intervention (in this case, people's weight before and after attending a weight loss boot camp) to determine if the treatment had a significant effect on the variable of interest (weight loss).

Yes, your answers seem to be correct!

For the z test, the question focuses on comparing a specific sample (college students in this case) to a larger population (college students in general). This test is useful for determining whether the sample is representative of the population or if there are significant differences.

For the t test for independent samples, the question is comparing two different groups (11th graders and 10th graders in junior highs) to see if there is a significant difference in a specific variable (unexcused absences). This test helps to determine whether there is a statistically significant difference between two independent groups.

For the t test for dependent samples, the question is investigating whether there is a significant change within the same group of people (people attending a weight loss boot camp) over a given time period (2 months). This test is useful for comparing the means of two related samples to determine if there is a significant difference.