Answer
a) Exact number
b) Exact number
c) Measured quantity subject to uncertainty
d) Measured quantity subject to uncertainty
Work Step by Step
a) The number of pages in this text can be counted. A result of counting is an exact number.
b) The number of days in the month of January is also a result of counting within the definitions of day and January. So there are no errors in measurement, which makes that it is an exact number.
c) The area of a city lot cannot be counted but has to be measured, so it is a measured quantity subject to uncertainty.
d) The distance between the centers of the atoms in a gold medal can be measured by chemists. So it is a measured quantity subject to uncertainty.
