Andrew measure the amount of a very unstable substance to be 100 moles. The half life of this substance is 3 days (after 3 days, half is gone).

This is what I have so far to solve this table. ( y = amount of substance and x is time in days)

Days Amount

-3(3 days prior) 200

0 100

3 50

6 25

9 12.50

12 6.25

(This is using y = 100(.5) ^x/3

How would I graph this information from the table?

How do I calculate the expected amount of substance if Andrew had take his measurement 9 days earlier? Show the calculations and consider the trend of the graph from above.

Would the calculation be y = 100(.5) ^x/9 ?

thanks