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An auditorium has 21 rows of seats. The first row has 18 seats and each succeeding row has 2 more seats than the previous row. How many seats are in the auditorium?

Respuesta :

shimelisabraham99

Answer:

798

Step-by-step explanation:

So, 21*{2*18 + (21-1)*2}/2

= 21*{36 + 20*2}/2

= 21*{36+40}/2

= 21*76/2

= 1596/2

= 798

Total number of seats is 798

Given that;

Number of seats in first row = 18

Number of rows = 21

Each row added number of seats then previous = 2

Find:

Total number of seats

Computation:

Total number of seats = Sn = (n/2)[2a + (n-1)d]

Total number of seats = Sn = (21/2)[2(18) + (21-1)2]

Total number of seats = (21/2)[36 + (20)2]

Total number of seats = (21/2)[36 + 40]

Total number of seats = (21/2)[76]

Total number of seats = (21)(38)

Total number of seats = 798

Learn more:

https://brainly.com/question/16668552?referrer=searchResults

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