Assignment 3 pandas

Good day
how do i use the .unique to retrieve data

how do i calculate life expentancy

The .unique() function is applied on a Pandas Series Object i.e on one Column of a dataframe at a time, it is used to extract the unque values from a single column
Follow the link to get better details about unique()

The overall life expectancy of the world is,

life expectancy per country * Population of the country / Total Population of the World