Hello,

the general form of the equation which describes exponential decay is:

is the amount at the time t

is the initial amount

k isa constant factor which spcify the speed of decaying(?)

You know that there are left only 0.4985 ml after the first second. This allows us to calculate the constant k:

will give

Therefore the equation of the function is:

As you may have noticed . You can only use this property for small values of k.