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Find the number of theater seats in an auditorium with 50 rows where the first row has 20 seats and each successive row has 2 more seats than the previous?

 Feb 12, 2017

Best Answer 

 #1
avatar
+5

This forms an arithmetic progression:

 

Sum=N/2[2F + (N -1)*D]

Sum =50/2[2*20 + (50 -1)*2]

Sum =25[40 + 98]

Sum =25 x 138

Sum =3,450 - number of seats in the theater.

 Feb 12, 2017
 #1
avatar
+5
Best Answer

This forms an arithmetic progression:

 

Sum=N/2[2F + (N -1)*D]

Sum =50/2[2*20 + (50 -1)*2]

Sum =25[40 + 98]

Sum =25 x 138

Sum =3,450 - number of seats in the theater.

Guest Feb 12, 2017
 #2
avatar+37168 
+5

Another way:

501 20 + 2(n-1) = 3450 seats

 Feb 12, 2017
 #3
avatar+26397 
0

Find the number of theater seats in an auditorium with 50 rows where
the first row has 20 seats and
each successive row has 2 more seats than the previous?

 

Formula:

tn=t1+(n1)dsn=(t1+tn2)n

 

n=50t1=20d=2t50=20+(501)2t50=20+492t50=118s50=(20+1182)50s50=(1382)50s50=6950s50=3450

 

The number of theater seats in an auditorium is 3450

 

laugh

 Feb 13, 2017

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