Uranium-238 decays to form thorium-234 with a half-life of 4.5 * 10⁹ years.How many years will it take for 75% of the uranium-238 to decay?

Question

Quizplus · Accepted Answer

After one half-life (4.5 billion years), 50% of the uranium-238 would have decayed, leaving 50%. After another half-life (another 4.5 billion years, totaling 9 billion years), half of the remaining 50% would decay, leaving 25% and meaning 75% has decayed.

Uranium-238 Decays to Form Thorium-234 with a Half-Life of 4