Note that each test's description starts with "The chance-in-six to" - that means the test is rolled on a d6 and an equal or lower number is required for a success. For example, the notation 3:6 means a roll of 1, 2, or 3 would succeed on the d6.
Similarly, for extraordinary feat the table notes the chance in %, meaning the roll is made with a d100, an equal or lower roll resulting in success (so if you have 4% to succeed with an extraordinary feat, only a roll of 01, 02, 03, or 04 on the d100 would net a success).