Permutations and Combinations

Question

The income of a person is Rs. 3,00,000 in first year and he receives an increase of Rs. 10,000 to his income per year for next 19 years. Find the total amount, he received in 20 years.

Answer

Here, a = 3,00,000, d = 10,000, n = 20

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= 10 (7,90,000) = 79,00,000.