Science HELP 2nd question
posted by sam .
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?

See the other post. Same formula.

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.