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$Consider the A.P a_{1}, a_{2}, a_{3} \dots a_{n}, the G.P b_{1}, b_{2} \dots b_{n} such that a_{1} = b_{1} = 1 : a_{9} = b_{9}$ $and \sum_{i = 1}^{9} a^{r} = 369 then$

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b6=27

b7=27

b8=81

b9=18

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Correct option is B

a1=b1=1,a9=1+8d=bn=1.r8∑r=19 ar=921+a9=921+r8=369 sum of n terms A.P=n2a+l ⇒r=3b7=b1r6=1.(3)6=27

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Consider the A.P a1,a2,a3…an, the G.P b1,b2…bn such that a1=b1=1:a9=b9 and ∑i=19 ar=369 then

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$Consider the A.P a_{1}, a_{2}, a_{3} \dots a_{n}, the G.P b_{1}, b_{2} \dots b_{n} such that a_{1} = b_{1} = 1 : a_{9} = b_{9}$ $and \sum_{i = 1}^{9} a^{r} = 369 then$