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Assume a parent isotope has a half-life of 100 million years. How old is a sample that
contains 15% of its original parent isotope?
250 million years
270 million years
200 million years
100 million year

Assume a parent isotope has a halflife of 100 million years How old is a sample that contains 15 of its original parent isotope 250 million years 270 million ye class=

Respuesta :

Answer:

270 million

Explanation:

1/2 ^n  = .15            (.15 is 15% in decimal)

                    log both sides

n log (1/2) = log (.15 )

   n = 2.737 half lives

EACH half life is 100 million

      2.737 * 100 million = 273.7 million

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