A refinery produces 3 grades of gasoline: Regular (85% octane), Mid-grade (90% octane), and Premium (95% octane). If 200 barrels of Regular, 100 barrels of Mid-grade, and 100 barrels of Premium are mixed, what is the average octane rating?

Correct option is A

Given:

Regular: 200 barrels at 85% octane

Mid-grade: 100 barrels at 90% octane

Premium: 100 barrels at 95% octane

Formula Used:

Average Octane = $$\frac{\sum (\text{volume} \times \text{octane})}{\sum \text{volume}}$$​​

Solution:

Total octane content = $$(200 \times 85) + (100 \times 90) + (100 \times 95)$$​

= 17000 + 9000 + 9500 = 35500 

Total volume = 200 + 100 + 100 = 400 barrels

Average Octane = $$\frac{35500}{400}$$​ = 88.75%