Answer:
The quantity of coffee costing $4 a pound in the coffee mixture is 2 pounds.
Step-by-step explanation:
Given: Coffee costing $4 a pound is mixed with 3 pounds of coffee costing 4.50 a pound to obtain a mixture costing $4.30 a pound.
We have to find the quantity of coffee costing $4 a pound in the mixture.
Let x represent the number of pounds of $4 coffee.
Cost of one pound = 4x.
Cost of 3 pounds of coffee costing 4.50 a pound = 3(4.50)
Cost of mixture costing $4.30 a pound = (x+3)(4.30)
According to given problem,
![4x+3(4.50)=(x+3)4.30](https://tex.z-dn.net/?f=4x%2B3%284.50%29%3D%28x%2B3%294.30)
Solving for x, we get,
![\Rightarrow 4x+13.5=4.30x+12.9](https://tex.z-dn.net/?f=%5CRightarrow%204x%2B13.5%3D4.30x%2B12.9)
Rearranging like term together, we get,
![\Rightarrow 13.5-12.9=4.30x-4x](https://tex.z-dn.net/?f=%5CRightarrow%2013.5-12.9%3D4.30x-4x)
![\Rightarrow 0.6=0.30x](https://tex.z-dn.net/?f=%5CRightarrow%200.6%3D0.30x)
![\Rightarrow x=2](https://tex.z-dn.net/?f=%5CRightarrow%20x%3D2)
Thus, the quantity of coffee costing $4 a pound in the coffee mixture is 2 pounds.