Calculus
posted by <3 .
The halflife of Palladium100 is 4 days. After 12 days a sample of Palladium100 has been reduced to a mass of 4 mg. What was the initial mass (in mg) of the sample? What is the mass 5 weeks after the start?

amountremaining=Initialamount*e^(.692t/4)
put in given: amount remaining, 12 days, solve for initial amount. 
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