Final answer:
The only discrete variable in the list provided is 'Number of students in a class', as it represents a countable number of individuals that cannot be fractional. The correct option is b.
Step-by-step explanation:
The student's question concerns discrete and continuous variables. Discrete variables are countable in a finite amount of time and cannot have fractional values, whereas continuous variables are measurable and can take on any value within a range, including fractions and decimals.
For the variables listed:
- a) Height of individuals: This is a continuous variable because it can be measured to any level of precision, such as 175.5 cm.
- b) Number of students in a class: This is a discrete variable because you can only have a whole number of students in a class.
- c) Temperature in degrees Celsius: This is a continuous variable as temperature can be recorded to decimal points, such as 22.5 degrees Celsius.
- d) Time taken to complete a task: This is continuous if measured precisely (like 3.25 hours), but it can be discrete if it's measured in whole units only (like 3 hours).
In this context, the correct answer to the question is:
- b) Number of students in a class - This is a discrete variable. The correct option is b.