Posted by **Emily** on Friday, October 29, 2010 at 8:05pm.

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.

- Math -
**Reiny**, Friday, October 29, 2010 at 10:12pm
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

- Math -
**sherri**, Thursday, April 5, 2012 at 9:33pm
what are two different expressions for the total number of seats in the auditorium

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