# SOLUTION: I sent this problem several days ago with no response. The level of thorium in a sample decreases by a factor one-half every 4.2million years A meteorite is discovered to have only

Algebra ->  Algebra  -> Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: I sent this problem several days ago with no response. The level of thorium in a sample decreases by a factor one-half every 4.2million years A meteorite is discovered to have only      Log On

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 Question 165826: I sent this problem several days ago with no response. The level of thorium in a sample decreases by a factor one-half every 4.2million years A meteorite is discovered to have only 7.6% of its original thorium remaining. How old is the meteorite?Answer by ankor@dixie-net.com(15746)   (Show Source): You can put this solution on YOUR website!This same problem came up about a week ago, here is what I submitted then : The level of thorium in a sample decreases by a factor of one-half every 4.2 million years. A meteorite is discovered to have only 7.6% of its original thorium remaining. How old is the meteorite? : The decay formula: Ao*2^(-t/h) = A Where: Ao = initial amt A = resulting amt t = time (in millions of yrs) h = half-life of the substance (in millions of years) : In this problem: let Ao = 1; A = .076 1*2^(-t/4.2) = .076 : ln(2^(-t/4.2)) = ln(.076); find the nat log of both sides : .693 = -2.577; use the log equiv of exponents : = -2.577; Multiply both sides by 4.2 -.693t = -2.577 * 4.2 : -.693t = -10.823 t = t = 15.6 million years old ; : Check solution on a calc enter 2^(-15.6/4.2) = .076.. :