Identify the discrete variables. A. Number of students in each class of a…
2026
Identify the discrete variables.
A. Number of students in each class of a school
B. Number of heads obtained in ten tosses of a coin
C. Marks scored by students in an objective type examination with negative marking for incorrect responses
D. Height of students in a school
Choose the correct answer from the options given below:
Answer: A. A, B and C Only — A variable is discrete if it can take only distinct, separate values (usually whole numbers) obtained by counting, with no possible value between two…
- A.
A, B and C Only
- B.
A and B Only
- C.
A, B and D Only
- D.
C and D Only
Show answer & explanation
Correct answer: A
A variable is discrete if it can take only distinct, separate values (usually whole numbers) obtained by counting, with no possible value between two consecutive counts. A variable is continuous if it can take any value, including fractions and decimals, within a given range, obtained by measurement.
The number of students in each class of a school is counted as whole students — 0, 1, 2, and so on — with no fractional student possible, so this is discrete.
The number of heads obtained in ten tosses of a coin can only be a whole number from 0 to 10, so this is discrete.
The marks scored in the objective exam with negative marking are built from a fixed score per question and a fixed deduction per wrong answer, so the total for a fixed-length test is always one of a finite, specific set of possible values, so this is discrete.
The height of students in a school is obtained by measurement and can take any value within a range — for example 152.3 cm or 152.34 cm — so this is continuous, not discrete.
Quantity | How its value arises | Variable type |
|---|---|---|
Number of students in each class | Counting whole students | Discrete |
Number of heads in ten tosses | Counting, limited to 0–10 | Discrete |
Marks in the objective exam with negative marking | Fixed award per correct answer minus fixed penalty per wrong answer, over a fixed number of questions | Discrete |
Height of students | Measurement on a scale, any value in a range | Continuous |
Cross-check: between any two heights, say 150 cm and 151 cm, infinitely many intermediate values (150.5 cm, 150.55 cm, and so on) are possible — this is exactly the property of a continuous variable, and it is why the height of students cannot be grouped with the other three quantities above. By contrast, the number of students, the number of heads, and the total marks can each only take one value from a finite, specific list for any given scenario — there is no in-between value possible the way there is for a measured quantity, confirming all three as discrete.
Hence, the number of students, the number of heads in ten tosses, and the marks scored in the objective exam are the discrete variables, while the height of students is continuous — matching the option that selects exactly these three quantities.