Mathematics - Sequence & Series Question with Solution | TestHub

MathematicsSequence & SeriesG.P.Medium2 min

MathematicsMediumsingle choice

The ratio of sum of first three terms of a G.P. to the sum of first six terms is $64 : 91$ , the common ratio of G.P. is

Answer:

Solution:

Given $\frac{S _{3}}{S _{6}} = \frac{64}{91} = \frac{a ( r ^{3} - 1 )}{a ( r ^{6} - 1 )}$

$\Rightarrow \frac{( r ^{3} - 1 )}{( r ^{3} + 1 ) ( r ^{3} - 1 )} = \frac{64}{91} \Rightarrow r^{3} = \frac{27}{64} ∴ r = \frac{3}{4}$

Stream:JEESubject:MathematicsTopic:Sequence & SeriesSubtopic:G.P.

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