Answered

A rock has 12.5 percent of its original amount of potassium-40 remaining in it; potassium-40 has a half-life of 1.25 billion years. How long ago was the rock formed?

A1.25 billion years ago

B2.5 billion years ago

C3.75 billion years ago

D5 billion years ago

Verified Answer :

Hagrid

A rock has 12.5 percent of its original amount of potassium-40 remaining in it; potassium-40 has a half-life of 1.25 billion years. 3.75 billion years ago was the rock formed. the answer is letter C

ktrose1602

Answer:

the answer is b) 2.5 billion years.  if its half life is 1.25 billion years and there is only 25% of the element remaining, you would take 1.25 billion and multiply it by two to get 2.5 billion.

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