ISTQB Exam Questions on Equivalence Partitioning and Boundary Value Analysis

Writing test cases based on Equivalence Partitioning and Boundary Value Analysis is a crucial skill that all testers should possess.

Recognizing this, the ISTQB Foundation Level Certificate exam places significant emphasis on it. Proper practice and critical thinking can greatly simplify the task of answering these questions.

This guide will share some examples of ISTQB Exam Questions on Equivalence Partitioning and Boundary Value Analysis and their correct answers.

Let the learning begin!

What Does Equivalence Partitioning Mean?

Equivalence Partitioning is a technique used to develop test cases. In this technique, equivalence classes (for input values) are identified. Each member of a class triggers the same type of processing and generates the same output.

The values at the boundaries (start/end values or lower/upper-end values) of such a class are called Boundary values. The method of examining a system’s behavior using these values is referred to as Boundary Value Analysis (BVA).

Sample ISTQB Exam Questions on Equivalence Partitioning and Boundary Value Analysis

Here are several practice questions from ISTQB exam papers for Equivalence Partitioning and BVA. (Ordered: Easy to slightly complex)

Q #1) One of the fields on a form contains a text box that accepts numeric values in the range of 18 to 25. Identify the invalid Equivalence class.

a) 17
b) 19
c) 24
d) 21

Answer:

The text box accepts numeric values in the range of 18 to 25 (including 18 and 25). This range forms our valid class. However, we’re asked to identify invalid equivalence classes. These classes are as follows:
Class I: values < 18   => invalid class
Class II: 18 to 25       => valid class
Class III: values > 25 => invalid class

The value 17 falls under an invalid class. Whereas 19, 24, and 21 fall under the valid class.

The answer is ‘A’.

Q #2) In an Examination, a candidate has to score a minimum of 24 marks to pass. The maximum he can score is 40 marks.  Identify Valid Equivalence values if the student passes the exam.

a) 22,23,26
b) 21,39,40
c) 29,30,31
d) 0,15,22

Answer:

The classes are as follows:
Class I: values < 24   => invalid class
Class II: 24 to 40       => valid class
Class III: values > 40 => invalid class

We need to identify Valid Equivalence values. These will fall within a Valid Equivalence class. All the values should be in Class II.

The answer is ‘C’.

Q #3) One of the fields on a form contains a text box that accepts alphanumeric values. Identify the Valid Equivalence class.

a) BOOK
b) Book
c) Boo01k
d) Book

Answer:

Alphanumeric values combine alphabets and numbers. Therefore, we must choose an option that includes both. A valid equivalence class will have both alphabets and numbers. Option ‘c’ includes both alphabets and numbers.

The answer is ‘C’.

Q #4) The Switch is turned off when the temperature goes below 18 and it’s turned on when the temperature is more than 21. Identify the Equivalence values that belong to the same class.

a) 12,16,22
b) 24,27,17
c) 22,23,24
d) 14,15,19

Answer:

We need to choose values from the same class (whether valid or invalid). The classes are as follows:

Class I: less than 18 (switch turned off)
Class II: 18 to 21
Class III: above 21 (switch turned on)

Only in Option ‘c’, all the values are from one class. Hence, the answer is ‘C’. (Please note that this question doesn’t ask about valid or invalid classes, just about values in the same class)

Q #5) A program validates numeric fields as follows: values less than 10 are rejected, values between 10 and 21 are accepted, values greater than or equal to 22 are rejected. Which of the following input values cover all the equivalence partitions?

a) 10,11,21
b) 3,20,21
c) 3,10,22
d) 10,21,22

Answer:

We need to select values that cover all equivalence classes (both valid and invalid).

The classes are as follows:

Class I: values < 10   => invalid class
Class II: 10 to 21       => valid class
Class III: values >= 22 => invalid class

All values from option ‘c’ fall under different equivalence classes.

The answer is ‘C’.

Q #6) A program validates numeric fields as follows: values less than 10 are rejected, values between 10 and 21 are accepted, values greater than or equal to 22 are rejected. Which of the following covers the MOST boundary values?

a) 9,10,11,22
b) 9,10,21,22
c) 10,11,21,22
d) 10,11,20,21

Answer:

The classes have already been determined as shown in question 5. The boundaries are 9, 10, 21, and 22. These four values are in option ‘b’.

The answer is ‘B’

Q #7)

Within a system designed to calculate payable taxes:
An employee receives £4000 of salary tax-free.
The next £1500 is taxed at 10%.
The next £28000 thereafter is taxed at 22%.
Any additional amount is taxed at 40%.

To the nearest whole pound, which of these groups of numbers fall into three DISTINCT equivalence classes?
a) £4000; £5000; £5500
b) £32001; £34000; £36500
c) £28000; £28001; £32001
d) £4000; £4200; £5600

Answer:

The classes are as follows:
Class I   : 0 to £4000          => tax-free
Class II  : £4001 to £5500   => 10% tax
Class III : £5501 to £33500 => 22% tax
Class IV : £33501 and above => 40% tax

We need to select values that fall into three different equivalence classes. Option ‘d’ has values from three distinct equivalence classes.

The answer is ‘D’.

Q #8)

Within a system designed to calculate payable taxes:
An employee receives £4000 of salary tax-free.
The next £1500 is taxed at 10%.
The next £28000 thereafter is taxed at 22%.
Any additional amount is taxed at 40%.

To the nearest whole pound, which of these is a valid Boundary Value Analysis test case?

a) £28000
b) £33501
c) £32001
d) £1500

Answer:

The classes have already been divided in question #7. We need to select a value that is a boundary value (start/end value). The value is 33501.

The answer is ‘B’.

Q #9) Given the following specifications, which of the following values for age are in the SAME equivalence partition?

If you are younger than 18, you are too young for insurance.
If you are between 18 and 30 inclusive, you will receive a 20% discount.
Anyone over 30 is not eligible for a discount.

a) 17, 18, 19
b) 29, 30, 31
c) 18, 29, 30
d) 17, 29, 31

Answer:

The classes are as follows:

Class I: age < 18       => uninsured
Class II: age 18 to 30 => 20% discount
Class III: age > 30     => no discount

In this scenario, we can’t determine which classes are valid or invalid, as it isn’t specified in the question. (However, we could infer that Classes I and II are valid and III is invalid. Though this isn’t required.) We need to select values that are in the SAME equivalence partition. The values from option ‘c’ fall in the same partition.

The answer is ‘C’.

These are some practice questions from ISTQB exam papers. We will continue adding more questions with answers from ISTQB exams in future posts.

About the Author: This is a guest article by N. Sandhya Rani. With around four years of experience in Software Testing, primarily in Manual Testing, she is assisting many aspiring software testers to clear the ISTQB testing certification exam.

Please leave your questions related to the ISTQB exams in the comment section below.

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