md file is missing. You should also upload the github markdown file, otherwise the code outputs (e.g. tables, figures etc) are not visible for us. So it's hard to judge whether the code output the corresponding figures/tables.
The coding is well formatted. However, it would be better that you can put some comments inside the code blocks to just give us some explanation.
For task 3, you should compute a trimmed mean of life expectancy for different years. However, you only output the vanilla mean. For task 4, I think you should create the table with life expectancy changing over the year.
All questions have been done and the overall work is good.
Peer Review hw-03 for Bill1111:
Remarks: