Alberto is stacking firewood. He puts 20 logs on the bottom row. Then he stacks each row so that there is 1 fewer log than the row below. Which of the following is formed by the number of logs in 10 rows?
A. an arithmetic series
B. an arithmetic sequence
C. a geometric series
D. a geometric sequence
The number of logs in each row would give an arithmetic sequence, as it decreases by 1 each time. Finding the total number of logs in 10 rows would be finding the sum, which makes it an arithmetic series.
