Question

There is an auditorium with 35 rows of seats. There are 20 seats in the first row, 22 seats in the second row, 24 seats in the third row, and so on. Find the number of seats in the twenty fifth row.

Answer 1

The number of seats arranged row wise are as follows : 20, 22, 24, ...

This sequence is an A.P. with

a = 20, d = 22 – 20 = 2, n = 25

\(\therefore\) The number of seats in the twenty fifth row is 68.