The volume of an object expressed in spherical co-ordinates is given by
$$V = \int\limits_0^{2\pi } {\int\limits_0^{{\raise0.5ex\hbox{$\scriptstyle \pi $} \kern-0.1em/\kern-0.15em \lower0.25ex\hbox{$\scriptstyle 3$}}} {\int\limits_0^1 {{r^2}} \,Sin\phi \,drd\phi \,d\theta .} } $$ The value of the integral

If $$\,\,\,x = a\left( {\theta + Sin\theta } \right)$$ and $$y = a\left( {1 - Cos\theta } \right)$$ then $$\,\,{{dy} \over {dx}} = \,\_\_\_\_\_.$$

From a pack of regular playing cards, two cards are drawn at random. What is the probability that both cards will be kings, if the card is NOT replaced?

The following data about the flow of liquid was observed in a continuous chemical process plant

Mean flow rate of the liquid is