All the questions are clearly answered. The content is organized properly.
Most Material covered in lectures are utilized and explored
Adding the link to md file and Rmd file in README.md making the repo easy to navigate.
Weaknesses
The data is represented in raw format. If you can organize the result to table, it should be easier to read.
The plots are not shown in the md file, probably you need to knit the rmd to show the plots.
For question 3. We should find the trimmed mean or weighted mean. However in your response, only vanilla mean is provided.
For question 5. First we need to determine the benchmark. From the homework, you apparently use the mean of worldwide life expectancy as the benchmark. I think reasoning should be added regarding why you choose this as benchmark.
Remarks:
Strenghths
Weaknesses