If \[{{S}_{n}}\]denotes the sum of first n terms of an A.P. and \[\frac{{{S}_{3n}}-{{S}_{n-1}}}{{{S}_{2n}}-{{S}_{2n-1}}}=31\], then the value of n is

If \[{{S}_{n}}\]denotes the sum of first n terms of an A.P. and \[\fra

1.	If \[{{S}_{n}}\]denotes the sum of first n terms of an A.P. and \[\frac{{{S}_{3n}}-{{S}_{n-1}}}{{{S}_{2n}}-{{S}_{2n-1}}}=31\], then the value of n is
A.	21
B.	15
C.	16
D.	19
Answer» C. 16

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If \[{{S}_{n}}\]denotes the sum of first n terms of an A.P. and \[\frac{{{S}_{3n}}-{{S}_{n-1}}}{{{S}_{2n}}-{{S}_{2n-1}}}=31\], then the value of n is

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