thanks Andrei but my question is I have already calculated the TCID50 of the virus. but now I want to know the volume of virus I have to add in a 25 cc flask (3*10^6 cells) at 100 TCID50. the titre of the virus is 10^6 TCID50/µl
The 10^6 TCID50/05 µl, it means that if you dilute virus stock in 10^6 times you will obtained 1 infection dose of virus. You need 1000 infections dose. Thus you need will prepare the volume which needed for 25 cc flask. (about 2 ml solution contain 1000 infections dose of virus).