Can you also help me with another one, it has a cone on top of a cylinder

The cones slant height is 6in
The cones length(radius) is 4 in
The cones height is not known
The cylinders height is 7 in
The cylinders length(radius) is also 4 in
The radius is half of the cylinder, cone
I don't know what to do, I need to find the total volume of the model , can you also tell me when do I use pi?