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Arock 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?
a) 1.25 billion years ago
b) 2.5 billion years ago
c) 3.75 billion years ago
d) 5 billion years ago
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Arock has 12.5 percent of its original amount of potassium-40 remaining in it; potassium-40 has a h...
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