ja, yo is correct, just expand that formula with your calculator
each one is 5% bigger than pevious
each one=previous+previous*5%
each one=previous*1+previous*0.05
each one=previous*(1+0.05)
each one is 1.05 times of previous
so after n years, if today year size is P then
[tex]A=P(1.05)^n[/tex]
A=final size
so ya, after 18 years, n=18 so you get
[tex]A=859(1.05)^{18}[/tex]
A=2067.29 microliters