1. Given:
Initial Amount
Ao = 30g
m= 1 Multiplying Factor
2
Period
p = 8 days
A = ? Final Amount
t Time that has passed
The formula we are using is..
A = Ao(m)(t/p)
1

2. How much will remain of the 30g sample in the following time:
a.) 2 weeks = 14 days
First, change the weeks into days since the half life of the substance is in days.
Then, substitute the given values to the equation.
A = Ao(m)(t/p)
A = 30 (1/2)(14/8)
A = 8.9191
8.9191 g will remain in 2 weeks.
2

3. b.) 278 days
A = Ao(m)(t/p)
A = 30(1/2)(278/8)
A = 1.0 x 10­9
1.0 x 10­9 g will remain in 278 days.
c.) 1 year = 365 days
First, change the year into days. There are 365 days in a year.
Then, substitute the given values to the equation.
A = Ao(m)(t/p)
A = 30(1/2)(365/8)
A = 5.5 x 10­13
5.5 x 10­13 g will remain in 1 year.
3

4. d.) 24 weeks = 168 days
First, change the weeks into days since the half life of the substance is in days.
Then, substitute the given values to the equation.
A = Ao(m)(t/p)
A = 30(1/2)(168/8)
A = 1.4 x 10­5
1.4 x 10­5 g will remain in 24 weeks.
4