Example 6 pounds of coffee at a certain price is mixed with 4 pounds of coffee costing 1 $ per pound less . The price of the mixture is 5 $ per pound. Find the price of the dearer kind.

Solution :

You are looking for the price of the dearer kind of coffee.

Let it be $ x per pound, then 6 pounds of this kind cost $ 6 x

If the price of the cheaper coffee is $ (x-1),

then 4 pounds of this kind costs $ 4 (x - 1).

Setting up the equation as

$ 6 x + $ 4 ( x - 1) = $ 50

i. e. 6 x + 4 x - 4 = 50

10 x = 54

x = 5.4

Therefore, the price of the dearer kind of coffee is $ 5.4 per pound.

Check: 6 lbs at $ 5.4 cost = $ 32.4

4 lbs at $ 4.4 cost = $ 17.6

Total cost = $ (32.4 + 17.6 = 50)

\ The price of the mixture is = $ 5 per kg.

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Index

9.1 - Definition and Solving Techniques
9.2 - Use of Simultaneous Linear Equations

Chapter 1