The age of Amit is same as Sumit because they are twins, Richa is younger than Sumit, Richa is younger than Jyotsana but elder than Saurabh , Sumit is younger than Jyotsana. Who is the eldest among them?

The age of Amit is same as Sumit
Amit = Sumit,
Richa is younger than Sumit
Sumit > Richa
Richa is younger than Jyotsana
Jyotsana > Richa
Sumit is younger than Jyotsana
Jyotsana > Sumit
Finally
Amit = Sumit, Sumit > Richa
Jyotsana > Richa > Saurabh
Jyotsana > Sumit
On arranging the above data, we get
∴ Jyotsana > Sumit= Amit > Richa > Saurabh
So, Jyotsana is eldest among them.