MHR • Advanced Functions 12 Solutions 660

Chapter 7 Practice Test Question 9 Page 410
!
a) 41 = 50 1 $
"
# 2%
&
0.82 = 1 2
10
h
10
h
log0.82 = 10 h log 1 2
10
h = log0.82
log 1 2
h =
h &= 35
10log 1 2
log0.82
The half-life is approximately 35 min.
!
b) 0.01 = 1 $
"
# 2%
&
t
35
log0.01 = t
35 log 1 2
t
35 = log0.01
log 1 2
t = 35log0.01
log 1 2
t &= 232.5
It will take approximately 232.5 min (approximately 3 h, 52 min, and 30 s) for the material to
decay to 1% of its initial amount.
MHR • Advanced Functions 12 Solutions 747