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ritznca ritznca
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11 years ago
A laboratory has 20 grams of a radioactive substance that decays in such a way that t days later the number of grams left will be y = 20(1/10)t/15 . How much will be present after 10 days?
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wrote...
#1
11 years ago
t=10

plug in

solve
wrote...
#2
11 years ago
y(t) = 20(0.1)^(t/15)

=> y(10) = 20(0.1)^(2/3)

i.e. After 10 days, 4.31 grams remain.

Slight Smile>
wrote...
#3
11 years ago
Radioactive decay normally entails an exponential function.  Are you sure it is not ^(t/15) ?
Taking what you have written as correct, t= 10 so y = 20 x (1/10) x 10/15 = 2 x 2/3 = 4/3  i.e. 4/3 days -  possible, but unless you are in a class that is not senior enough to have met exponential functions, I'd say you have an error.
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