If $9^{a-2}÷3^{a+4}={81}^{a-11}$, then find the value of $3^{a-8}+3^{a-6}$.

The variance $p$, $q$, $r$, and $s$ are correlated with each other with the following relationship: $\frac{s^{0.5}}{p}=\frac{q}{r^2}$

The ranges of values for $p$, $q$ and $r$ are respectively:

$-0.04\le p\le -0.03$, $-0.25\le q\le -0.09$, $1\le r\le 7$

Determine the difference between the maximum and minimum value of $s$?

If the graph $y=f\left(x\right)$ is shown in the diagram below, then answer the following question:

If $f\left(x\right)=0$ has '$n$' real roots then n$=$?

If the graph $y=f\left(x\right)$ is shown in the diagram below, then answer the following question:

Sum of all roots of $f\left(x\right)=0$ is:

If the graph $y=f\left(x\right)$ is shown in the diagram below, then answer the following question:

Total number of roots of $f\left(x\right)=2$ is: