The ratio of students packing a lunch to those buying a lunch is 2:9. The number of students buying lunch is how many times the
2 answers:
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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.
