Let $x _{1}, x _{2}, x _{3}, \ldots ., x _{20}$ be in geometric progression with $x_{1}=3$ and the common ration $\frac{1}{2}$. A new data is constructed replacing each $x_{i}$ by $\left(x_{i}-i\right)^{2}$. If $\bar{x}$ is the mean of new data, then the greatest integer less than or equal to $\bar{x}$ is $.....$
$143$
$144$
$145$
$142$
Three numbers are in $G.P.$ such that their sum is $38$ and their product is $1728$. The greatest number among them is
The first term of a $G.P.$ whose second term is $2$ and sum to infinity is $8$, will be
The product $(32)(32)^{1/6}(32)^{1/36} ...... to\,\, \infty $ is
The numbers $(\sqrt 2 + 1),\;1,\;(\sqrt 2 - 1)$ will be in
Let $a _1, a _2, a _3, \ldots$ be a $G.P.$ of increasing positive numbers. Let the sum of its $6^{\text {th }}$ and $8^{\text {th }}$ terms be $2$ and the product of its $3^{\text {rd }}$ and $5^{\text {th }}$ terms be $\frac{1}{9}$. Then $6\left( a _2+\right.$ $\left.a_4\right)\left(a_4+a_6\right)$ is equal to