Free practice · multiple-choice · hard
Practice
Diagnose a wrong-base solution
A learner says an item that costs USD 68 after a 15% discount originally cost USD 78.20 because 68 × 1.15 = 78.20. Which statements correctly diagnose and repair the setup? Select all that apply.
Wrong-base diagnosis
Trace what each amount represents before repairing the formula
- Known
- USD 68 is the final price after a 15% discount
- Tempting error
- Treat the final price as the 100% base
- Relationship
- Final price represents the 85% remaining amount
- Control
- Recover the base, then reapply 0.85 and reconcile
A plausible calculator result is not enough. The setup must restore the unknown 100% base and reproduce the supplied final amount.