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
see attachment it will clear your doubt . example of finite countable set = no. of alphabets , no. of roots in quadratic polynomial .etc.... if any doubt then ask