what percent of a sample of a radioactive element whose half life=5.0 years will decay after 25 years?

Calculate the rate of decay constant for U-238 if its half-life is 4.468 × 109 years. If the problem is referring to the half-life, then the ratio of = 0.5 because half of the original sample has already undergone decay.

Explanation:

i think tornado but not 100%