Acertain radioactive isotope has a half-life of 15 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?

A half-life of the isotope is 15 days and at start its mass is 32 g.
A table:
              t:                 m:
              0                32 g
             15               16 g
             30                 8 g
             45                 4 g
             60                 2 g
             75                 1 g
In the first column is used an arithmetic sequence ( a 1 = 0, d = 15 ).
In the second column is used a geometric sequence ( a 1 = 32, r = 1/2 )                       

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