Question

there are 25 rows of seats in an Auditorium the first row is of 20seats the second row is of 22 seat the third row is of 24 seat and so on how many seats are there in the 21st floor ​

Answer 1

Answer:

AP series is = 20, 22, 24 _________

a = 20

common differnce = 2

now, we have to find seat on 21st floor :-

T21 = a+(n-1)d

= 20+(21-1)2

= 20+40

= 60 (Ans)

(Mark as brainlist)

Answer 2

Answer:

in this arithmetic progression you can find thier common difference ap = 22-20=2 hence the common difference between them is 2

t21= a(n-1)d

20(21-1)2

20¤40

=60