36.
(a) We use R = R
0
e
−λt
to find t:
t =
1
λ
ln
R
=
T
1/2
ln 2
14.28 d
3050
170
= 59.5 d .
(b) The required factor is
= e
λt
t ln 2/T
(3.48 d/14.28 d) ln 2
= 1.18 .