MCQ
The four arithmetic means between $3$ and $23$ are
  • A
    $5, 9, 11, 13$
  • $7, 11, 15, 19$
  • C
    $5, 11, 15, 22$
  • D
    $7, 15, 19, 21$

Answer

Correct option: B.
$7, 11, 15, 19$
b
(b) Let four arithmetic means are ${A_1},{A_2},\;{A_3}$ and ${A_4}$.

So $3,\;{A_1},\;{A_2},\;{A_3},\;{A_4},\;23$

$ \Rightarrow $ ${T_6} = 23 = a + 5d$

$ \Rightarrow $ $d = 4$

Thus ${A_1} = 3 + 4 = 7,\;{A_2} = 7 + 4 = 11,\;$

$A_3 = 11+4 =15 ,\, A_4 = 15+ 4=19$

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$1.$  The sum $V_1+V_2+\ldots+V_n$ is

$(A)$ $\frac{1}{12} n(n+1)\left(3 n^2-n+1\right)$

$(B)$ $\frac{1}{12} n(n+1)\left(3 n^2+n+2\right)$

$(C)$ $\frac{1}{2} n\left(2 n^2-n+1\right)$

$(D)$ $\frac{1}{3}\left(2 n^3-2 n+3\right)$

$2.$  $\mathrm{T}_{\mathrm{T}}$ is always

$(A)$ an odd number $(B)$ an even number

$(C)$ a prime number $(D)$ a composite number

$3.$  Which one of the following is a correct statement?

$(A)$ $Q_1, Q_2, Q_3, \ldots$ are in $A.P.$ with common difference $5$

$(B)$ $\mathrm{Q}_1, \mathrm{Q}_2, \mathrm{Q}_3, \ldots$ are in $A.P.$ with common difference $6$

$(C)$ $\mathrm{Q}_1, \mathrm{Q}_2, \mathrm{Q}_3, \ldots$ are in $A.P.$ with common difference $11$

$(D)$ $Q_1=Q_2=Q_3=\ldots$

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