The question is given from ncert Book of class 10th Chapter no. 5 Ex. 5.2 Q. 19. In the following question you have to find that when the salary of Subba Rao will become 7000 if he gets increment of 200 every year with the initial salary of 5000. Give the solution.

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# In 1995 Subba Rao started work at an annual salary of Rs 5000 and received an increment of Rs 200 every year. In which year did his income reach Rs 7000?

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Solution:i.e after 1995, the salary of each year are:

5000, 5200, 5400, …

a= 5000d= 200Let in nth year, his salary be Rs 7000.

i.e, by the nth term formula of AP,

a=_{n}a+(n−1)d7000 = 5000+(

n−1)200200(

n−1)= 2000(

n−1) = 10n= 11i.e in the 11th year, his salary will become Rs 7000.