ASVAB (Armed Services Vocational Aptitude Battery)Mathematics Knowledge (MK)Hard
A supply officer is tracking inventory. If the number of spare parts decreases by 15% each month, and there are currently 800 parts, how many parts will there be after 2 months?
- A595 parts
- B578 parts
- C680 parts
- D785 parts
Show answer & explanationAnswer & explanation
Correct answer: B. 578 parts
Month 1: 800 * (1 - 0.15) = 800 * 0.85 = 680 parts. Month 2: 680 * (1 - 0.15) = 680 * 0.85 = 578 parts.
Why the other options are wrong
- A. This is an incorrect calculation, possibly applying 15% to the original 800 twice (800 - 120 - 120 = 560) but with a slight error.
- C. This is the number of parts after only 1 month of decrease.
- D. This is an incorrect calculation, possibly 800 - 15.
Percentage Decrease (Compound)
Applying a percentage reduction repeatedly to a declining base value.
- Each decrease is calculated on the new, reduced amount.
- Expressed as (1 - rate) for each period.
- Used in depreciation, population decline, etc.
Memory trick: Percentages are Powerful for Predicting Progress.