1- It's probably the cheapest book in the shop.
2- She's probably the nicest girl in the village.
3- It's probably the funniest story in the book.
4- It's probably the quickest train in England.
5- It's probably the coldest place in Scottland.
6- Its probably the better cake in the shop.
7- It's probably the easiest exercise in the book.
8- He's probably the most successful businessman in London.