Questions

When a thread is created the threads does not require any new resources to execute the thread shares the resources like memory of the process to which they belong to. The benefit of code sharing is that it allows an application to have several different threads of activity all within the same address space. Whereas if a new process creation is very heavyweight because it always requires new address space to be created and even if they share the memory then the inter process communication is expensive when compared to the communication between the threads.

To get a pair of black rings 100 percent certain

27 blue + 17 red + 2 black = 40 rings should be taken out

Then only we can get 100 % a pair of black rings.