Uranium -238 has a half-life of 4.5 billion years. When the Earth was formed, there was twice as much uranium -238 present as there is now. What is the age of the Earth?

## Step 1:We know that the half-life of an element is the amount of time for the original mass to diminish by 50%.## Step 2:Given that Uranium-238 has a half-life of 4.5 billion years, this means if we started with a certain amount of Uranium-238, after 4.5 billion years, only 50% of that amount will remain, the rest will have decayed.## Step 3:We are told that "When the Earth was formed, there was twice as much uranium-238 as there is now." This implies that Earth has experienced exactly one half-life, since half of the original amount of Uranium-238 when Earth formed has decayed and half remains.### Therefore by following the principle of half-life of uranium