According to the question,
Lakshmi is elder than Meenu
Lakshmi > Meenu
Leela is elder than Meenu but younger than Lakshmi
Lakshmi > Leela > Meenu
Latha is younger than both Meenu and Hari but Hari is younger than Meenu
Meenu > Hari > Latha
On arranging the above data, we get
Lakshmi > Leela > Meenu > Hari > Latha
Hence, Latha is the youngest.