SOLUTION: An auditorium has 50 rows of seats. The first row has 20 seats, the second has 21, each row having 1 more seat than the previous. How many seats are there together?
(I figured i
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(I figured i
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Question 176989This question is from textbook Mathmatics for Elementary Teachers
: An auditorium has 50 rows of seats. The first row has 20 seats, the second has 21, each row having 1 more seat than the previous. How many seats are there together?
(I figured it out by multiplying 50x20, and then adding the product with the sum of 49+48..., but I do not know a short cut or formula to get the answer) This question is from textbook Mathmatics for Elementary Teachers
You can put this solution on YOUR website! There are 20 seats in the first row and 20 + 50 - 1 = 69 seats in the last row. You need the sum of the integers from 20 to 69 inclusive.
20 plus 69 = 89
21 plus 68 = 89
and so on
You have 25 (50 divided by 2) such pairs that add to 89, so 25 X 89 = 2225
In general, the sum of a series of integers is where a is the first integer, l is the last integer, and n is the number of integers.
