How much time would it take for 9000 atoms of nobellium-253 (half-life is 97 s) to decay to 2250 atoms?

Question

a)291 s

b)97 s

c)48.5 s

d)194 s
Please help ASAP!!! :(

Answer 1

My bad it's actually a Science question :D

Answer 2

(1/2)^n = 2250 / 9000 = 1/4

n = 2

2 half-lives