Question

Black Eyed Peas’ 2011 Live Concert is to take place in a circular park. Due to the shape of the area, seats are set up so that the innermost row has 64 seats and each successive row has 17 more seats than the row before it. The park’s open area can accommodate 17 rows of seats in this pattern. What is the maximum number of tickets that can be distributed if everyone who has a ticket is guaranteed a seat?

Answer 1

so you are adding
64 + 81 + 98 + ... for 17 terms

a = 64
d = 17
n = 17

use the formula
Sum(17) = (17/2)[128 + 16(17)]
= 3400