Review the following video. According to the video problem, you are required to do:

1. Please take a piece of paper and write down the process of establishing confidence intervals step by step.

2. According to past experience, 20% of students took public transportation. Test if the situation changed. Solve the problem step by step.

3. You are required to solve both problems and write it down, take a picture of them, and put them into a PDF file. Upload your pdf file here.

Confidence Interval for a Population Proportion

https://youtu.be/np-CwMl-O1M