ACT (Enhanced)MathematicsEasy
A quality control manager is inspecting a batch of 200 items. She finds that 15% of the items are defective. How many items in the batch are NOT defective?
- A170 items
- B185 items
- C15 items
- D30 items
Show answer & explanationAnswer & explanation
Correct answer: A. 170 items
If 15% are defective, then 100% - 15% = 85% are NOT defective. Calculate 85% of 200: 0.85 * 200 = 170 items.
Why the other options are wrong
- B. This would be 92.5% of 200, or a miscalculation.
- C. This is 15 items, not 15% of 200. It's too low.
- D. This is 15% of 200, which represents the number of defective items, not non-defective.
Percentage of a Quantity
Calculating a specified percentage of a given total quantity, often involving finding the complement percentage.
- Percentages are parts per hundred.
- To find 'x%' of a number, multiply the number by x/100.
- The 'complement' percentage is 100% minus the given percentage.
Memory trick: Percent Part: Find the complement, then multiply by total!