There are 15 rows of seats in an auditorium. the first row has 20 seats, and each of the other rows has 5 more seats than the row in front. which of the following is formed by the number of seats in each row?
a. an arithmetic series
b. an arithmetic sequence
c. a geometric series
d. a geometric sequence

Option B. An arithmetic sequence

Step-by-step explanation:

There are 15 rows of seats in an auditorium. The first row has 20 seats, and each row has 5 more seats than the row in front.

This means sequence formed for seats will be

20, (20+5), (20+5+5), (20+5+5+5)20 rows

Or 20, 25, 30, 35, 40,20 rows

Since every term of this sequence is 5 more than its previous term.

Means there is a common difference of 25 - 20 = 5

Therefore, the sequence formed is an arithmetic sequence.

Please note it's a sequence because it has finite terms. If the sequence has infinite terms then this sequence will be called as series.

Option B. Arithmetic sequence is the answer.