Ten cups of a restaurant's house Italian dressing is made up by blending olive oil costing $1.30 per cup with vinegar that costs $0.25 per cup. How many cups of vinegar are used if the cost of the blend is $0.78 per cup?

Question

Quizplus · Accepted Answer

The cost of the blend per cup ($0.78) is a weighted average of the costs of olive oil ($1.30 per cup) and vinegar ($0.25 per cup). Let $x$ be the number of cups of vinegar. Then, the number of cups of olive oil is $10 - x$. The total cost of the blend is $10 \times 0.78 = 7.8$. Setting up the equation for the total cost: $1.30(10 - x) + 0.25x = 7.8$. Solving for $x$ gives $x = 5$, meaning 5 cups of vinegar are used.

Ten Cups of a Restaurant's House Italian Dressing Is Made