An auditorium has 50 rows of seats. The first row has 20 seats, the second row has 21, the third row has 22 seats, and so on, each row having one more seat than the previous row. How many seats are there all together?

Question

An auditorium has 50 rows of seats.  The first row has 20 seats, the second row has 21, the third row has 22 seats, and so on, each row having one more seat than the previous row.  How many seats are there all together?
a.	write 2 different expressions for the total number of seats in the auditorium.  One expression should use addition:  the other should involve multiplication.  Write an equation that uses these two expressions.
b.	Solve the auditorium problem, explaining your reasoning.

Reiny · Accepted Answer

Your problem is dealing with an arithmetic series, where a=20 , d=1, and n = 50 Sum(n) = n/2[2a + (n-1)d] = 25[40 + 49(1)] = 2225

sherri · Answer

what are two different expressions for the total number of seats in the auditorium

Heather · Answer

2225

... · Answer

wrong though ^^^

Person B · Answer

Its pretty difficult. Not an answer just a comment.