Let a1, a2,……..a3n be an arithmetic progression with a1 = 3 and a2 = 7. If a1 + a2 + ….+a3n = 1830, then what is the smallest positive integer m such that m (a1 + a2 + …. + an) > 1830?
Correct Answer :
9
Solution :
The correct option is B.
Given the first term of the arithmetic progression (AP) is and the second term is .
The common difference of the AP is:
The sum of the first terms is given as 1830:
Substitute and into the equation:
Solving the quadratic equation:
Since must be a positive integer, we have .
Now, let's find the sum of the first terms, i.e., :
We need to find the smallest positive integer such that:
Thus, the smallest positive integer satisfying this inequality is 9.
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