# SOLUTION: How long will it take a sample of radioactive substance to decay half of its original amount, if it decays according to the function A(t) = 450e^-0.249t , where t is the time in y

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 Click here to see ALL problems on logarithm Question 212012: How long will it take a sample of radioactive substance to decay half of its original amount, if it decays according to the function A(t) = 450e^-0.249t , where t is the time in years? Round to the nearest hundreth year. choices (in years): 2.78 112.05 24.54 27.32Answer by ankor@dixie-net.com(15628)   (Show Source): You can put this solution on YOUR website!How long will it take a sample of radioactive substance to decay half of its original amount, if it decays according to the function A(t) = 450e^-0.249t , where t is the time in years? Round to the nearest hundredth year. : Half of original amt: 450/2 = 225 [A(t)] : = 225 divide both sides by 450 = = .5 then log equiv of exponents -.249t*ln(e) = ln(.5) ln of e is one so we have: -.249t = -.693 t = t = 2.78 yrs : : Check solution on a calc; enter: 450*e^(-.249*2.78)= 225.2 half the original amt