Question

In a group, every member knows at least one of the languages Hindi and Urdu. $100$ members know Hindi, $50$ know Urdu and $25$ of them both Hindi and Urdu. How many members are there in the group

Answer 1

As it is given that every member know at least one language.

And number of prsons knowing Hindi $=n\left(H\right)=100$

number of prsons knowing Urdu $=n\left(U\right)=50$

number of prsons knowing both $=n(H\cap U)=25$

Hence $n\left(HUU\right)=n\left(H\right)+n\left(U\right)-n(H\cap U)=100+50-25=125$

Hence the total number of members = 125