Time management is very much important in IIT JAM. The eduncle test series for IIT JAM Mathematical Statistics helped me a lot in this portion. I am very thankful to the test series I bought from eduncle.
Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Deepak singh 1
This symbol is greek letter pronounced as ' Xi ' . It is used in many field of mathematics. its not used fixed symbol. It is used sometimes to denote set/collection , as variables in ODE/PDE , to denote series/sequence ,etc...