-The number of B cells producing the antibody is proportional to the concentration of that antibody.
-On day 16, one out of 100000 B cells are specific for antigen A
\frac{1}{100000} = 1 x 10⁻⁵ B cells
- on day 16, Antibody concentration is 2 × 10¹= 20 Antibodies
- on day 36, antibody concentration 8 × 10³.= 8000
20 antibodies ------------ 1 x 10⁻⁵ B cells
8000 antibodies--------------x
x= (8000 x 1 x 10⁻⁵)/ 20
x= 4x10⁻³ or 1 in 250 are B cells specific for antigen A