SOLUTION: THE AMOUNT OF A RADIOACTIVE TRACER REMAINING AFTER t DAYS IS GIVEN BY A=Aoe^0.18t, WHERE Ao IS THE STARTING AMOUNT AT THE BEGINNING OF THE TIME PERIOD. HOW MUCH SHOULD BE ACQUIRED

Algebra ->  Points-lines-and-rays -> SOLUTION: THE AMOUNT OF A RADIOACTIVE TRACER REMAINING AFTER t DAYS IS GIVEN BY A=Aoe^0.18t, WHERE Ao IS THE STARTING AMOUNT AT THE BEGINNING OF THE TIME PERIOD. HOW MUCH SHOULD BE ACQUIRED      Log On


   

Question 64133: THE AMOUNT OF A RADIOACTIVE TRACER REMAINING AFTER t DAYS IS GIVEN BY A=Aoe^0.18t, WHERE Ao IS THE STARTING AMOUNT AT THE BEGINNING OF THE TIME PERIOD. HOW MUCH SHOULD BE ACQUIRED NOW TO HAVE 40 GRAMS REMAINING AFTER 3 DAYS?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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THE AMOUNT OF A RADIOACTIVE TRACER REMAINING AFTER t DAYS IS GIVEN BY A=Aoe^0.18t, WHERE Ao IS THE STARTING AMOUNT AT THE BEGINNING OF THE TIME PERIOD. HOW MUCH SHOULD BE ACQUIRED NOW TO HAVE 40 GRAMS REMAINING AFTER 3 DAYS?
:
I think the equation should be: A = Ao(e^-.18t)

Substitute 40 for A, and 3 for t, solve for Ao:
Ao*(e^-.18(3)) = 40
:
Ao*(e^-.54) = 40
:
On a good calc find e^.-54
Ao * .5827 = 40
Ao = 40/.5827
Ao = 68.64 grams