Standard Deviation about Median

Q. If the standard deviation of $0,1,2,\mathrm{3...9}$ is $K$, then the standard deviation of $10,11,12,\mathrm{13...19}$ is

1. $K+10$
2. $K$
3. $\sqrt{10}+K$
4. $10K$

Q. Find the standard deviation for the following data:
$\begin{array}{cccccc}{x}_i& 3& 8& 13& 18& 23\\ f_i& 7& 10& 15& 10& 6\end{array}$

1. 5.37
2. 15.92
3. 6.12
4. 13.87

Q. In an A.P., let $T_n$ denotes the $n^{th}$ term and $S_n$ denotes the sum of first $n$ terms. If $T_7=\frac{1}{9}$ and $T_9=\frac{1}{7},$ then the value of $S_{63}$ is

1. $32$
2. $49$
3. $56$
4. $63$