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half life help?

half life help?

BubbleLover98

Uranium decays into lead. the half life of uranium is 4,000,000,000 years. A sample of radioactive rock contains 7 times as much lead as it does uranium. Calculate the age of the sample.

Reply 1

KombatWombat

I guess you're assuming all the lead came from uranium decay, and 7 times as much refers to number of atoms instead of mass, so what fraction of the original amount of uranium is still uranium? How many half lives is this? Once you know how many half lives you can calculate the age of the sample.

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