52 For each of the following situations define an appropriat

5.2 For each of the following situations, define an appropriate random variable and state whether it is continuous or discrete.

a) An astronomer observes the number of stars in a quadrant of the sky.

b) A physician records the diastolic blood pressure of a study participant.

c) A forester measures the diameter at breast height (dbh) of trees.

d) A pathologist is looking for signs of disease in blood samples.

Explain why...

5.2 For each of the following situations, define an appropriate random variable and state whether it is continuous or discrete. a An astronomer observes the number of stars in a quadrant of the sky. b A physician records the diastolic blood pressure of a study participant. c A forester measures the diameter at breast height (dbh) of trees d A pathologist is looking for signs of disease in blood samples.

Solution

Note that discrete variables can only take certain values; continuous variables can take any value on a specified range.

5.2

a) variable: number of stars in a quadrant; DISCRETE. You can only have an integer number of stars.

b) Variable: diastolic blood pressure; CONTINUOUS, as it can take any value on a reasonable range of pressures.

c) variable: diameter at breast height of trees; CONTINUOUS. It can take any value on a reasonable range of diameters.

d) variable: Number of bacteria per mL of blood; DISCRETE, as it can only take integer values.