hardMultiple Choice
FC0-U71 Practice Question: A developer is testing a piece of code that…
A developer is testing a piece of code that calculates discounts. The code should give 10% off for orders over $100, and 5% off for orders between $50 and $100. Which test input set would best verify boundary conditions?
⚠ Common exam trap
The trap here is that candidates often pick Option A or C, thinking that testing the exact boundary values ($50, $100) is sufficient, but they miss the need to test values just outside the boundaries to catch off-by-one or floating-point comparison errors.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
$49.99, $50.00, $99.99, $100.00, $100.01
It tests the exact boundary values for the discount tiers: $49.99 (just below $50, no discount), $50.00 (5% threshold), $99.99 (still 5%), $100.00 (boundary between 5% and 10%), and $100.01 (10% threshold). This set validates both the lower and upper edges of each range, ensuring the code handles floating-point comparisons correctly.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
$50, $100, $150
Why it's wrong here
These values test only the exact boundaries, missing just-inside and just-outside cases such as $49.99, $50.01, $100.01 and $99.99, where off-by-one errors surface. It tempts because boundary testing targets limits, but effective boundary sets include values immediately either side of each threshold.
- ✗
$0, $50, $100, $200
Why it's wrong here
Omits values just below boundaries and uses integer values only, not precise for boundary testing.
- ✗
$50.00, $100.00
Why it's wrong here
Testing only $50.00 and $100.00 exercises the two thresholds themselves but omits values immediately either side, so an off-by-one error in the `>` and `>=` comparisons stays hidden. Boundary-value analysis pairs each boundary with its neighbours; $49.99, $50.01, $99.99 and $100.01 would expose those faults.
- ✓
$49.99, $50.00, $99.99, $100.00, $100.01
Why this is correct
These values sit exactly on and just outside each threshold: $50.00 and $100.00 are boundaries, while $49.99, $99.99 and $100.01 test just below and above. This exercises the 5% and 10% discount transitions, satisfying the boundary-condition requirement.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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