Question

a meeting hall has 26 in the First row 24 season 2 second row 2018 third row and so on and has in all 30 Rose how many seats are there in the meeting hall​

Answer 1

Answer:


Step-by-step explanation:

The no. of seats in each row are as follows 20, 24, 28, .........


The no. of seats in each row form an A.P. with


First term (a) = 20


Difference between the no. of seats in two successive rows (d) = 4


Total no. of rows (n) = 30


Total no. of seats in 30 rows (S30) = ?


Sn = n/2[2a + (n – 1) d]

∴ S30 = 30/2 [2 (20) + (30 – 1) 4]

∴ S30 = 15 [40 + 116]

∴ S30 = 15 (156)

∴ S30 = 2340

∴ Total no. of seats in the meeting hall is 2340.

Answer 2

Sol. The no. of seats in each row are as follows 20, 24, 28, .........


The no. of seats in each row form an A.P. with


First term (a) = 20


Difference between the no. of seats in two successive rows (d) = 4


Total no. of rows (n) = 30


Total no. of seats in 30 rows (S30) = ?


Sn = n/2[2a + (n – 1) d]

∴  S30 = 30/2 [2 (20) + (30 – 1) 4]

∴  S30 = 15 [40 + 116]

∴  S30 = 15 (156)

∴  S30 = 2340

∴ Total no. of seats in the meeting hall is 2340