How much Uranium-235 would be left if the fossil were approximately 350 million years old? in mg

Question

How much Uranium-235 would be left if the fossil were approximately 350 million years old? in mg

Answer 1

That depends on how much (in mg) that you had to start with.

The half life of U-235 is about 700,000,000 years. That means that every 700,000,000 years on half of the original amount has decayed.

Dividing 350 million years by 700,000 years gives a half of a half life.

So...in 700, 000 years, you have half the original amount left. After 350,000 billion years, you have three-quarters half of the original amount left.

So...just multiply that by the original amount in milligrams and you have the remaining amount in milligrams