Yes those mixtures are correct but dont add any water at all. With patios, the idea is that the compressed sand will create a unmovable based which give your patio is already down, it will be.
The pointing sand is there to stop it moving about by packing it, eventually the moisture of rain or in the air will bind the 50/50 mix together, if you really want to you can sprinkle it with a watering can but I never do, as it weakens the sand and you have to keep packing more and more in as it leaches down and makes a right mess.
It also means that you can sweep away the excess without it sticking to your slabs. As it will leave nasty concrete marks if you don't clean it off adequately.
The pointing sand is there to stop it moving about by packing it, eventually the moisture of rain or in the air will bind the 50/50 mix together, if you really want to you can sprinkle it with a watering can but I never do, as it weakens the sand and you have to keep packing more and more in as it leaches down and makes a right mess.
It also means that you can sweep away the excess without it sticking to your slabs. As it will leave nasty concrete marks if you don't clean it off adequately.