The certain amount of principle becomes 7200 in 2 years and 7800 in 3 years, in simple interest. Find the principle.

Answer: A. 6000

In simple interest, the interest earned each year stays the same. Subtracting the 2-year amount from the 3-year amount gives 1 year of interest: (7,800 - 7,200 = 600). Therefore, the total interest earned over the first 2 years is (600 times 2 = 1,200). Subtracting this 2-year interest from the 2-year total amount gives the original principal: (7,200 - 1,200 = 6000).

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