Question

The first row of a school concert hall has 25 seats and each row after the first has one more seat than the row before it there are 32 rows of seats write the rule or equation for the number of seats in the nth row 35 students from the class want to sit in the same row in which row can they sit together? What is the seating capacity of the concert hall? Suppose each seat in rows 1 through 11 of the concert hall costs 100 each seat in rows 12 through 22 costs 75 and each seat in rows 23 through 32 costs 50 how much money does the concert hall take in for a sold out event?

Answer 1

you have an AP with
a = 25
d = 1
The nth row has a + (n-1)d seats
The $1.00 seats are rows 1-11, so
S11 = 1.00 * 11/2 (2*25+10*1)

Row 12 has 25+11 = 36 seats, so the 11 rows of $0.75 seats cost
0.75 * 11/2 (2*36+10*1)

and so on