Eva, Josh, and David gather and shell pecans for their mother. Eva gathers 2 1/2 pounds of pecans, Josh collects 3.25 pounds, an
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Answer:
It will take 7 years ( approx )
Step-by-step explanation:
Given equation that shows the amount of the substance after t years,
Where,
= Initial amount of the substance,
If the half life of the substance is 19 years,
Then if t = 19, amount of the substance = ,
i.e.
Taking ln both sides,
Now, if the substance to decay to 78% of its original amount,
Then
Again taking ln both sides,
Hence, approximately the substance would be 78% of its initial value after 7 years.