Answer
Exact b,d,f
Inexact a,c,e
Work Step by Step
Exact Numbers have values that are known exactly, and inexact values have uncertainty to them, normally due to measurement. Measurement A is inexact, because every index card will have minute differences that alter the mass. B is exact, because a pound will always have 16 ounces. C is inexact because the volume of the coffee isn't standardized, it has potential to change. D is exact because there will always be the same amount of inches in a mile. E is inexact because the number of microseconds is so large that it is subject to small differences. F is exact because the book always has the same number of pages.
