Q46 of 176 Page 8

The income of a person is Rs. 300000 in the first year and he receives an increase of Rs. 10000 to his income per year for the next 19 years. Find the total amount he received in 20 years.

The income of a person in 1st year = Rs 300000


The income of a person in 2nd year = Rs 300000 + 10000


= Rs 310000


The income of a person in 3rd year = Rs 310000 + 10000


= Rs 320000


and so,on


Therefore, the AP is


300000, 310000, 320000,…


Here a = 300000, d = 310000 – 300000 = 10000


and n = 20


We know that,




⇒ S20 = 10 [600000 + 190000]


⇒ S20 = 10[790000]


⇒ S20 = 7900000


Hence, the total amount he received in 20 years is Rs 7900000.


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