Question 888215
Plug in y = a/2 and solve for t



y = a*e^(-0.0736t)


a/2 = a*e^(-0.0736t)


1/2 = e^(-0.0736t)


ln(1/2) = ln(e^(-0.0736t))


ln(1/2) = -0.0736t*ln(e)


ln(1/2) = -0.0736t*1


ln(1/2) = -0.0736t


ln(1/2)/(-0.0736) = t


9.41776060543403 = t


t = 9.41776060543403



The halflife is approximately 9.41776060543403 (use whatever units are part of the problem)