Question

for each variable, determine whether it is best thought of as discrete or continuous.
variable
(a) the number of damaged chromosomes on a petri dish following irradiation
(b) the highest grade level (1st, 2nd, or 3rd) completed by a high - school dropout
(c) the cranial capacity (space inside the skull) of a human skull
(d) the number of defective compact discs in a batch of 500 discs
discrete

continuous

Explanation:

Step1: Recall the definitions of discrete and continuous variables

A discrete variable has a countable number of possible values. A continuous variable can take on any value within a certain interval.

Step2: Analyze each variable

• (a) The number of damaged chromosomes: This is a countable quantity. So it is a discrete variable.
• (b) The highest grade level: There are only 3 possible values (1st, 2nd, 3rd). So it is a discrete variable.
• (c) Cranial capacity: This can take on any value within a range (e.g., 1000 - 1500 cc). So it is a continuous variable.
• (d) The number of defective compact discs: This is a countable quantity. So it is a discrete variable.

Answer:

(a) Discrete, (b) Discrete, (c) Continuous, (d) Discrete