A radioactive substance has half-life 5 years. The probability of decay in 10 years, in percent, is 3n. Find n.
Physics · Nuclear physics
JEE Mains Advanced

Question

A radioactive substance has half-life 5 years. The probability of decay in 10 years, in percent, is 3n. Find n.

G1 Physics · Accepted Answer

After 10 y = 2 half-lives, survival probability is (1/2)²=1/4, so decay probability is 3/4=75%. Since 75=3n, n=25.