Anyone familiar with Data Management?

Need help to pass course , this school year since exams are coming up and I can not really find a tutor because my guidance counsellor said its to late in the semester to request one and my parents or I cannot afford one. Therefore, I need help to catch up and I'm having trouble with the following questions...

I'm very lost in this course right now , so I really need explaining of what it all means.

Question 1 - Sampling - Collecting Data

5) Explain the similarities and difference between stratified sampling and cluster sampling

6) you are hired by a factory to survey the employees about their work conditions. The following table list the number of employees working in each division

Table

Divison Number of employees

Hamilton division - 250

Sudbury division - 230

Oshawa division - 110

Kingston division - 40

a) Design a stratified sample to survey 10 % of the employee

b) Suggest two other ways to stratify this sample

7. Classify the bias in each of the following scenarios.

a) Students at university are asked if the first year is as hard as other claim it to be.

b) A travel magazine wants to know the annual travel budget of its subscribers. It sends a survey to 1000 randomly selected subscribers.