If the $p^{th}$ term of a harmonic progression is $qr$ and the $q^{th}$ term is $pr$,then what is its $r^{th}$ term?

The $4^{th}$ term of a $H.P.$ is $\frac{3}{5}$ and $8^{th}$ term is $\frac{1}{3},$ then its $6^{th}$ term is

If $a, b, c$ are in $G.P.$,then $\log_a x, \log_b x, \log_c x$ are in:

If $\ln(a+c), \ln(c-a), \ln(a-2b+c)$ are in $A.P.$,then

If $a, b, c$ are in $H.P.$,then the value of $\left( \frac{1}{b} + \frac{1}{c} - \frac{1}{a} \right) \left( \frac{1}{c} + \frac{1}{a} - \frac{1}{b} \right)$ is

Let $a, b, c, p, q$ and $r$ be positive real numbers such that $a, b$ and $c$ are in $GP$ and $a^{p} = b^{q} = c^{r}$. Then,