ATI TEAS (Test of Essential Academic Skills) Version 7MathematicsMedium
A patient's blood glucose level was 180 mg/dL. After administering insulin, the level dropped to 135 mg/dL. What is the percentage decrease in the patient's blood glucose level?
- A33%
- B20%
- C25%
- D45%
Show answer & explanationAnswer & explanation
Correct answer: C. 25%
Percentage decrease is calculated as: ((Original Value - New Value) / Original Value) * 100%. So, ((180 - 135) / 180) * 100% = (45 / 180) * 100% = 0.25 * 100% = 25%.
Why the other options are wrong
- A. This is approximately the percentage increase if 135 was the original and 180 the new, but not the decrease.
- B. This would be a decrease of 36 mg/dL from 180 mg/dL.
- D. This is the absolute difference (45 mg/dL), not the percentage decrease.
Percentage Decrease
The relative reduction in a quantity, expressed as a percentage of the original quantity.
- Formula: ((Original Value - New Value) / Original Value) * 100%.
- Always based on the original value.
- Used to quantify reductions or improvements.
Memory trick: Difference over Original, then multiply by 100, that's the percentage you've done!