A collector of rare items is negotiating with a museum. He wants to sell a spear he claims to have been used to kill a mammoth over 11,000 years ago. A spear that size would have started with around 4g of
Carbon-14, and the museum tests show it now contains around 2g. How many half-lives have passed since the spear was carved?

I'm not sure if you maybe forgot to add in some information but I can give you the equation you will need to solve this..! (just without the bit of infomration you might need)

In this case you'll be solving for t and I can help you with your first step, you'll divide 2 by 4, getting you to:

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .

found in the nucleus

has mass of one amu