90% of a radioactive sample is left undecayed after time t has elapsed. What percentage of the initial sample will decay in a total time 2t:
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90% of a radioactive sample is left undecayed after time t has elapsed. What percentage of the initial sample will decay in a total time 2t:

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: 19%.