# Science HELP 2nd question

A sample originally contained 2.5 g of rubidium 87 now contains 1.25 g. The half life of rubidium - 87 is 6 x 10 ( to the 10th) years. How old is the sample? Is this possible? why or why not?

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1. See the other post. Same formula.

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bobpursley
2. 6 x 10^10 years old b/c it's exactly half of 2.5, Not possible b/c world hasn't existed for 60 trillion years.

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