Originally Posted by

**chocolatelover** Hi everyone,

Could someone please tell me if this is correct?

A cell divides into two cells every 20 minutes. The initial population of a culture is 60 cells

Find and expression for the number of cells after t hours:

(0,60) (20, 132)

132=600e^k20

ln2.2=lnk^20

ln2.2/20=20k/20

k=ln2.2/20

y(t)=60e^ln2.2/20t

Find the number of cells after 8 hours:

y(8)=60e^ln2.2/20(8)

Find the rate of growth after 8 hours:

Isn't that just -2.2% but it can't be negative. ???????????

When will the population reach 20,000 cells?

20000=60e^-2.207t

t=-2.63 This can't be right. It can't be a negative number, right?

Thank you very much