The correct answer is to cast one operand to double, as in (double) a / b. This works because Java performs integer division when both operands are integers, truncating the fractional part and yielding an incorrect whole number result like 0 instead of 0.5. By casting either a or b to double, the division becomes floating-point division, preserving the decimal value and producing a double result. On the Oracle Java Foundations 1Z0-811 exam, this concept tests your understanding of type promotion and the distinction between integer and floating-point arithmetic—a common trap is forgetting that dividing two ints always truncates, even when assigning to a double variable. A reliable memory tip is “cast one, not both”: converting just one operand is sufficient to trigger floating-point division, while casting the result after division is too late.
1Z0-811 Java Basics and Syntax Practice Question
This 1Z0-811 practice question tests your understanding of java basics and syntax. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A developer writes code to calculate the average of two integers: int a = 5; int b = 10; int avg = a / b;. Which change ensures the average is correctly calculated as a double?
Why wrong: Integer division truncates, so average is incorrectly 0.
B
Change the variable types to double
Why wrong: Changing variable types would work, but the question asks for a change to the existing code, not a complete rewrite; also this is not the minimal change.
C
Cast one operand to double: (double) a / b
Casting one operand to double ensures floating-point division.
D
Use Math.round(a / b)
Why wrong: Math.round still operates on integer division result, not a fix.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Cast one operand to double: (double) a / b
Option C is correct because in Java, when both operands of the division operator are integers, integer division is performed, truncating the fractional part. By casting one operand to double, the operation becomes floating-point division, yielding a double result (0.5). This ensures the average is calculated correctly as a double.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
No change needed; integer division is correct
Why it's wrong here
Integer division truncates, so average is incorrectly 0.
✗
Change the variable types to double
Why it's wrong here
Changing variable types would work, but the question asks for a change to the existing code, not a complete rewrite; also this is not the minimal change.
✓
Cast one operand to double: (double) a / b
Why this is correct
Casting one operand to double ensures floating-point division.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use Math.round(a / b)
Why it's wrong here
Math.round still operates on integer division result, not a fix.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Oracle often tests the misconception that changing variable types alone fixes integer division, but the trap is that integer literals (5 and 10) remain int unless explicitly cast or assigned to double variables before the division.
Detailed technical explanation
How to think about this question
In Java, binary numeric promotion occurs during arithmetic operations: if either operand is double, the other is converted to double before the operation. Casting one operand to double triggers this promotion, ensuring floating-point division. This is crucial in real-world scenarios like calculating averages in financial applications, where truncation would lead to significant rounding errors.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 1Z0-811 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Java Basics and Syntax — This question tests Java Basics and Syntax — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Cast one operand to double: (double) a / b — Option C is correct because in Java, when both operands of the division operator are integers, integer division is performed, truncating the fractional part. By casting one operand to double, the operation becomes floating-point division, yielding a double result (0.5). This ensures the average is calculated correctly as a double.
What should I do if I get this 1Z0-811 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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