Question

Suba Rao started work in 1995 at an annual salary of Rs 5000 and received a Rs 200 raise each year. In what year did his annual salary will reach Rs 7000?

Answer 1

Annual salary received by Suba Rao in 1995, 1996, 1997, . . . . is

Rs 5000, 5200, 5400, . . . .

Clearly, it is arithmetic progression with first term a = 5000 and commond difference d = 2000

Suppose Suba Rao's annual salary reaches to Rs 7000 in n^th year. Then n th term of the above A.P. = Rs. 7000 

⇒ a + (n – 1)d = 7000 

⇒ 5000 + (n – 1) × 200 = 7000 

⇒ (n – 1) × 200 = 2000 

⇒ n – 1 = 2000/200 

⇒ n – 1 = 10 

⇒ n = 10 + 1 = 11

Thus, 11th salary received by Suba Rao will be Rs 7000. This means that after 10 years i.e. in the year 2005 his annual salary will reach to Rs 7000.