What do exponential growth and decay have in common?

1 Answer
Mar 30, 2015

They both work with the same equation: #N=B*g^t#
Where
#N=# new situation
#B=# begin
#g=# growth factor
#t=# time

If the growth-factor is greater than #1#, then we have a growth.
If it is less than #1# we call it decay.
(if #g=1# nothing happens, a stable situation)

Examples:
(1) A population of squirrels, starting at 100, grows by 10% every year. Then #g=1.10# and the equation becomes: #N=100*1.10^t# with #t# in years.
(2) A radio-active material with original activity of 100, decays by 10% per day. Then #g=0.90# (because after a day only 90% will be left) and the equation will be: #N=100*0.90^t# with #t# in days.