The image contains mathematical calculations related to circle equations and a table for statistical data analysis, with a note 'Complete table 6 Marks'. The main question appears to be related to completing the table.

Comparing the given equation with the general form:

$$2gx = -4x \implies 2g = -4 \implies g = -2$$ $$2fy = -6y \implies 2f = -6 \implies f = -3$$ $$c = 9$$

The center is $(-g, -f)$.

$$\text{Center} = (-(-2), -(-3)) = (2, 3)$$

The radius is $r = \sqrt{g^2 + f^2 - c}$.

$$r = \sqrt{(-2)^2 + (-3)^2 - 9}$$ $$r = \sqrt{4 + 9 - 9}$$ $$r = \sqrt{4}$$ $$r = 2$$

The student's work for the circle equation is correct.
The center of the circle is $\boxed{(2, 3)}$ and the radius is $\boxed{2}$.

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: Complete Table for Assumed Mean

To complete the table and calculate the mean using the assumed mean method, we need to:

1. Choose an assumed mean ($A$). We will choose $A=13$ (the midpoint of the class with the highest frequency).
2. Determine the class width ($c$). The class intervals are not perfectly uniform (0-5 has width 6, 6-10 has width 5, 11-15 has width 5). We will use the most common class width, $c=5$, for the calculation of $u$.
3. Calculate the deviation $d = x - A$.
4. Calculate $u = \frac{x - A}{c}$.
5. Calculate $u^2$.
6. Calculate $Fu$ and $Fu^2$.
7. Sum the columns $\sum F$, $\sum Fu$, and $\sum Fu^2$.
8. Calculate the mean using the formula $\bar{x} = A + \frac{\sum Fu}{\sum F} \times c$.

Here is the completed table:

Marks	F	x	d = x - A	u = (x - A)/c	u^2	Fu	Fu^2	C.B
0-5	2	2.5	$2.5 - 13 = -10.5$	$\frac{-10.5}{5} = -2.1$	$(-2.1)^2 = 4.41$	$2 \times (-2.1) = -4.2$	$2 \times 4.41 = 8.82$	-0.5 - 5.5
6-10	8	8	$8 - 13 = -5$	$\frac{-5}{5} = -1$	$(-1)^2 = 1$	$8 \times (-1) = -8$	$8 \times 1 = 8$	5.5 - 10.5
11-15	13	13	$13 - 13 = 0$	$\frac{0}{5} = 0$	$0^2 = 0$	$13 \times 0 = 0$	$13 \times 0 = 0$	10.5 - 15.5
Total	23					-12.2	16.82

$$\bar{x} = A + \frac{\sum Fu}{\sum F} \times c$$

Substitute $A=13$, $\sum Fu = -12.2$, $\sum F = 23$, and $c=5$:

$$\bar{x} = 13 + \frac{-12.2}{23} \times 5$$ $$\bar{x} = 13 + \frac{-61}{23}$$ $$\bar{x} = 13 - 2.65217...$$ $$\bar{x} \approx 10.35$$

The completed table is shown above, and the mean is $\boxed{10.35}$.