Answer
a. sample
b. population
c. sample
d. population
Work Step by Step
a. The group of 25 patients represent only a portion from the populations.
b. All items produced on a machine are being studied from the year of 2001 to 2015.
c. 50 persons represent only a portion from the population.
d. 10 employees represent the population of the real estate agency during 2015.