Question 1077994
{{{Q=AB^t}}}


{{{0.75=1*B^40}}}, if starting amount were 1.

{{{log(10,0.75)=log(10,(B^40))}}}

{{{40*log(10,B)=log(10,0.75)}}}

{{{log(10,B)=log(10,0.75)/40}}}

{{{log(10,B)=-0.00312347}}}

{{{cross(B=1.00722)}}}

{{{B=0.9928}}}-----fixed


{{{cross(Q=A*(1.00722)^t)}}}
{{{highlight(Q=A(0.9928)^t)}}}


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{{{t[h]}}} Half-Life


{{{(1/2)=1*(0.9928)^t}}}

{{{log(10,0.9928^t)=log(10,1/2)}}}

{{{t*log(10,0.9928)=log(1/2)}}}

{{{t=log(10,1/2)/log(10,0.9928)}}}

{{{t=(-0.30103)/(-0.00312347)}}}

{{{highlight(t[h]=96)}}}---------96 minutes