If < {aₙ} > is an A.P . and a₁ + a₄ + ag + .......+ a_{16} = 147 , then a₁ + at

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8. Sequences and Series

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If $< {a_n} >$ is an $A.P$. and $a_1 + a_4 + a_7 + .......+ a_{16} = 147$, then $a_1 + a_6 + a_{11} + a_{16}$ is equal to

A

$96$

B

$98$

C

$100$

D

None

Solution

$a_{1}+a_{16}=a_{4}+a_{13}=a_{7}+a_{10}=\lambda$

$3 \lambda=147 \Rightarrow \lambda=49$

$a_{1}+a_{6}+a_{11}+a_{16}=2 \lambda=98$

Standard 11

Mathematics

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