determine half life of krypton-92 if only 6.0 millograms of an original 96.0 sample remains unchanged after 7.36 seconds

Answer 1

ln(No/N) = kt
No = 96
N = 6
k = unknown
t = 7.36 seconds.
Then substitute k into the below equation.
k = 0.693/t_1/2 and solve for t_1/2.

Answer 2

1.84 seconds