Question

A theater has 34 seats in the first row, 37 seats in the second row, 40 seats in the third row, and so on. How many seats are there in row 15?

There are _______  seats in row 15.

Answer 1

Formula: S_n = S_1st + (n - 1)d

where, S_n = the number of seats in n^th row

            S_1st = the number of seats in 1^st row = 34

            n = the last row = 15

            d = common difference in number of seats = 3

∴ S₁₅ = 34 + (15 -1)3

=> S₁₅ = 34 + 42 = 76 

Therefore, There are 76 seats in row 15. 

Answer 2

Here a theater has 34 seets in first row the der has 37 sects in second row a theter has no sects in third row can be written as {34:37, 40, -- -- tis ) :-( This where tis ios = adhetor has the number of seeds - in a row 15 The Here this sons of wat (1) is the arithmetric sequence term is since difference d between each consecutive constant we know that fn = at (2-1) Whore a= first rerm= 34 d = 3 : 715 = 33+ (15-1)x3 = 34 + 14x3 = 34+52 = 76 415 = 76 : There are [76) seers in row 15