Question

A sample of Strontium-90 is found to have decayed to one-eighth of its original amount after 87.3 years. What is the half-life of strontium-90?

87.3 years

43.7 years

29.1 years

10.9 years

Answer 1

is it 1/8 ?

Answer 2

What you mean?

Answer 3

about one-eighth

Answer 4

But thats not in the choices.
87.3 years

43.7 years

29.1 years

10.9 years

Answer 5

I know, one-eighth is same 1/8 ?

Answer 6

yes.

Answer 7

Nt = 1/8 No
Nt/No = 1/8

Nt/No = 1/2^(t/delta t)
1/8 = 1/2^(87.3/delta t)
delta t = 29.1

Answer 8

Oh okay, thanks.

Answer 9

:)