Luke L. answered 02/27/20
Recent MD graduate! Friendly, professional, and methodical.
2 hours = 120 minutes
If the generation time is 20 minutes, that means there are 6 generations in 120 minutes. Since you've started with 2 bacteria, Ni = 2.
Nt = Ni * 2^n
Nt = 2 * 2^6
Nt = 2 * 64
= 128 bacteria total after 6 hours
Please let me know if you need any additional support.