The mean and variance of 7 observations are 8 and 16 respectively.

Let $8,16, x_{1}, x_{2}, x_{3}, x_{4}, x_{5}$ be the observations.

Now $\frac{x_{1}+x_{2}+\ldots+x_{5}+14}{7}=8$

$\Rightarrow \sum_{i=1}^{5} x_{i}=42$    ..........(1)

Also $\frac{x_{1}^{2}+x_{2}^{2}+\ldots x_{5}^{2}+8^{2}+6^{2}}{7}-64=16$

$\Rightarrow \sum_{i=1}^{5} x_{i}^{2}=560-100=460$     ..........(2)

So variance of $x_{1}, x_{2}, \ldots, x_{s}$

$=\frac{460}{5}-\left(\frac{42}{5}\right)^{2}=\frac{2300-1764}{25}=\frac{536}{25}$