Q. 114.0( 1 Vote )

# Mark the correct alternative in the following:

In the arithmetic progression whose common difference is non-zero, the sum of first 3 n terms is equal to the sum of next n terms. Then the ratio of the sum of the first 2 n terms to the next 2 n terms is

A. 1/5

B. 2/3

C. 3/4

D. none of these

Answer :

Here, sum of first 3n terms=sum of next n terms

i.e. S_{3n}=S_{4n}-S_{3n}

i.e. 2S_{3n}=S_{4n}

----------(1)

Sum of 2n terms is S_{2n}_{and} sum of next 2n terms is given by S_{4n}-S_{2n}

Now,

(∵ using (1))

So, ratio of the sum of first 2n terms to the next 2n terms is 1:5

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