Answer:

Step-by-step explanation:
The exponential decrease formula that we must use is:

Where A is the amount of thorium as a function of time
is the initial amount and k is the decrease rate
We know that initially there are 50 gr and that you decay 50% every 1.9 years.
So


We solve the equation for k





After 22.8 years the amount of thorium that exists is:


Here time can take any value starting from 0 to 6 hours.
So we say that valid input can be all real number from 0 to 6 hours
Option C is correct
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Answer:
its is
Step-by-step explanation:
it is x vs minus 2