To calculate the value of the half life we proceed as follows; a/2=ae^(-2.360t) the a(s) will cancel and we shall remain with: 1/2=e^-2.360t introducing the natural logs we get: ln (1/2)=ln e^(-2.360t) ln(1/2)=-2.360t hence; t=(ln 0.5)/(-2.360) t=0.294 the answer is t=0.294