SOLUTION: A radioactive substance is decaying use the formula s=y(e raised to -0.04t) where y is initial amount and s is the amount remaining after t years. A.) If y = 50grams how much mas

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Question 1205428: A radioactive substance is decaying use the formula s=y(e raised to -0.04t) where y is initial amount and s is the amount remaining after t years.
A.) If y = 50grams how much mass will be left after 5 years of decay
B.) How long will it take for the mass to decay to half of the original mass (y = 50g)
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
s=ye%5E%28-0.04t%29
t is in years.
y, s, in grams.


(A)
how much still after 5 years?

s=50%2Ae%5E%28-0.04%2A5%29----------you can use the computational tool of your choice.

OR

s=50%2Ae%5E%28-0.2%29-----------and use the computational tool of your choice.


(B) Big hint
Take natural log of both sides of s=ye%5E%28-0.04t%29 and solve for t.