Question

a culture of bacteria doubles every 2hours if there are 500 bacteria in the begining how many bacteria will be there after 24hours ?

Answer 1

As it forms a GP with a = 500, r = 2 and n= 24/2 = 12 thus using
Sn = a(rn - 1)/(r - 1)   if r> 1
Sn = 500(2^ 12 - 1)/(12-1)
which you could calculate further to get an answer.