(Q29).Subba Rao started work in 1995 at an annual salary of Rs. 5000 and received an increment of Rs. 200 each year. In which year did his income reach Rs. 7000?

Given: Salary of Subba Rao in 1995 = Rs. 5000

Annual increment = Rs. 200

i.e., His salary increases by Rs. 200 every year.

equation (1) : a + d =

equation (2) : a + d =

-d = -

⇒ d =
-
-
 =

Clearly 5000, 5200, 5400, forms an A.P in which a = and d = .

Now suppose that his salary reached Rs. 7000 after x – years.

i.e., an =

But, an = a + (n – 1)d

= + (n – 1)

⇒ – = (n – 1)

⇒ n - 1 =
=

⇒ n = +

∴ In th year his salary reached Rs. 7000.