Calculate the standard deviation and variance of the frequency distribution below.

Let $x$ be the Age and $f$ be the Frequency.

Age (x)	Frequency (f)	fx	$x^2$	$fx^2$
6	4	24	36	144
7	6	42	49	294
8	10	80	64	640
9	11	99	81	891
10	8	80	100	800
11	1	11	121	121
Total	40	336		2890

From the table:

$$\sum f = 40$$ $$\sum fx = 336$$ $$\sum fx^2 = 2890$$

The formula for the mean of a frequency distribution is:

$$\bar{x} = \frac{\sum fx}{\sum f}$$ $$\bar{x} = \frac{336}{40}$$ $$\bar{x} = 8.4$$

The formula for the variance of a frequency distribution is:

$$\sigma^2 = \frac{\sum fx^2}{\sum f} - \bar{x}^2$$

Substitute the values:

$$\sigma^2 = \frac{2890}{40} - (8.4)^2$$ $$\sigma^2 = 72.25 - 70.56$$ $$\sigma^2 = 1.69$$

The variance is $\boxed{\text{1.69}}$.

The standard deviation is the square root of the variance:

$$\sigma = \sqrt{\sigma^2}$$ $$\sigma = \sqrt{1.69}$$ $$\sigma = 1.3$$

The standard deviation is $\boxed{\text{1.3}}$.