# What is the population parameter of interest? When the responses are normal?

#### crazymartin

##### New Member
The problems said:

Students in Stanford are supposed to spend on average 3 hours of time per week for every credit hour they take. Last year, 263 randomly selected seniors were contacted and asked how much total time they spent on their studies over the last week and how many credit hours they currently take.​

Below each question, I show my work.

(i) In this study, what is the population (be precise) and what is the sample?
Population: Senior Students in Stanford.
Sample: 263 Seniors in Stanford

(ii) What is the population parameter of interest? How could one compute a sample estimate of this population parameter?

Population parameter of interest: time per week by credit they take.
Sample estimate of the population parameter: sum of all the pop parameter over 263

(iii) Under which circumstances would it be reasonable to assume that the average time spent per credit hour computed from the responses is normally distributed?

n=263 sample mean= (no idea) true mean(the suposed)= (? 3hr )

Concerns: I have no idea if my answers for i and ii are correct, and I need help doing the last question. If someone can help me to understand this it will be appreciated, thanks a lot!

#### rogojel

##### TS Contributor
hi,
as far as ll goes, you have some inconsistency - you can not sum "all the population parameter", as that is one value. "Time per week per credit they take" is not well defined imho - time per each student in the sample or what do you mean.

For iii I guess there should be a paragraph in your textbook about this - The question is a bit vague with many possible answers, mayne check the central limit theorem?

I hope this helps a bit