An auditorium has 25 rows, with 10 seats in the first row, 12 in the second row, 14 in the third row, and so forth. How many seats are in the auditorium?
A) 850
B) 900
C) 550
D) 500

Question

Quizplus · Accepted Answer

The number of seats in each row forms an arithmetic sequence with the first term 10 and a common difference of 2. The number of seats in the nth row is given by 10 + (n-1)*2. The total number of seats is the sum of this arithmetic sequence for 25 terms: S = 25/2 * (2*10 + (25-1)*2) = 850.

An Auditorium Has 25 Rows, with 10 Seats in the First