Sherlock and His Device

Sherlock has finally caught Jim Moriarty in his own trap. Jim had called Sherlock to the amusement park to play one of his mind games, but he wasn't aware that the Sherlock had beforehand bugged the whole place with his newly invented device, which tells Sherlock the chances of Moriarty being at a particular place in the park. The design of the Amusement park if plotted on a graph is in the form