The half-life of substance X is 45 years, and it decomposes to substance Y. A sample from a meteorite was taken which contained 2% of X and 14% of Y by quantity of substance. If substance Y is not normally found on a meteorite, what is the approximate age of the meteorite?
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Question

The half-life of substance X is 45 years, and it decomposes to substance Y. A sample from a meteorite was taken which contained 2% of X and 14% of Y by quantity of substance. If substance Y is not normally found on a meteorite, what is the approximate age of the meteorite?

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G1 Physics · Accepted Answer

Step 1: Use N(t) = N₀ exp(−λt), A = λN and T₁/₂ = ln2/λ. Step 2: For two samples, write the decay law separately and equate the required activities/numbers. Final: B: 135 years.