Question

There is a group of persons each of whom can complete a piece of work in 16
days, when they are working individually. On the first day one person works, on
the second day another person joins him, on the third day one more person joins
them and this process continues till the work is completed. How many days are
needed to complete the work?​

Answer 1

I guess we can't do it coz we don't know the exact value of the work :)