Solve this equation: (in description)

Question

A radio active isotope decays according to the exponential decay equation where t is in days. 

 

Round to the thousandths place. 

 

For the half life: The half life is the solution (t) of the equation : a/2=ae^−5.1t

 

 

 

Answer 1

a/2 = ae^-5.1t  

1/2 = e^-5.1t  

ln(1/2) = ln(e^-5.1t) = -5.1t  

t = ln(1/2) / (-5.1)

  = 0.136  

 

Check:  e^-5.1*0.136 = e^-0.6936 = 0.4998 ~ 1/2