A certain radioactive isotope has a half-life of 11 days. If one is to make a table showing the half-life decay of a sample of this isotope from 32 grams to 1 gram; list the time (in days, starting with t = 0) in the first column and the mass remaining (in grams) in the second column, which type of sequence is used in the first column and which type of sequence is used in the second column?

Question

anonymous · Answer

0         32
11       16
22       8
33       4
44       2
55       1

anonymous · Answer

Start by writing out the first few entries for each column in the table they give you. What they are asking is for you to look for a pattern in EACH column individually.

anonymous · Answer

the first column is arithmetic since you are just adding 11 each time
second column is geometric, as the terms look like 
$$a, ar, ar^2, ar^3, ...$$ with $a=32,r=\frac{1}{2}$