# mixture question

• Aug 7th 2008, 12:02 PM
euclid2
mixture question
Conrad works at a bulk-food store. His manager asks him to mix some
dried fruit (that cost $3.75/kg) with some granola (that costs$1.75/kg) to
make 30 kg of trail mix that will sell for $2.75/kg. How many kilograms of dried fruit are in the trail mix? • Aug 7th 2008, 01:59 PM Chop Suey I drew this table to make things clearer for you. http://i529.photobucket.com/albums/d...y/Picture1.png The total price is found by multiplying the Price/Weight by Weight. Now, let's analyze the table. We can see that the total price is expressed as: $a + b = 82.5$ But we still need another relation. Let's go back to the table. We can see that the total weight is expressed as: $c + d = 30$ But what is c and d? Remember, they gave you the price/weight for dried fruits: $\frac{a}{c} = 3.75$ $\frac{b}{d} = 1.75$ Can you work your way from here? Hint: Try to write the total weight expression in terms of a and b. Then it only becomes a matter of simple substitution. :D • Aug 7th 2008, 03:06 PM Soroban Hello, euclid2! Quote: Conrad works at a bulk-food store. His manager asks him to mix some dried fruit that cost$3.75/kg
with some granola that costs $1.75/kg to make 30 kg of trail mix that will sell for$2.75/kg.
How many kilograms of dried fruit are in the trail mix?

Let $x$ = number of kilograms of fruit.
. . At $3.75/kg, its total value is: . $3.75x$ dollars. Write that into the first row of our chart. $\begin{array}{c|c|c|c|} & & \text{Unit} & \text{Total} \\ & \text{kg.} & \text{price} & \text{value} \\ \hline \text{Fruit} & x & \3.75 & 3.75x \\ \text{Granola} & & & \\ \hline \text{Mixture} & & & \end{array}$ Then $(30-x)$ = number of kilograms of granola. . . At$1.75/kg, its total value is: . $1.75(30-x)$ dollars.
Write that in the second row of our chart.

$\begin{array}{c|c|c|c|}
& & \text{Unit} & \text{Total} \\
& \text{kg.} & \text{price} & \text{value} \\ \hline
\text{Fruit} & x & \3.75 & 3.75x \\
\text{Granola} & 30-x & \1.75 & 1.75(30-x) \\ \hline
\text{Mixture} & & & \end{array}$

The final mixture is 30 kg of mix worth \$2.75/kg.
. . Its total value is: . $(30)(\2.75) \:=\:\82.50$
Write that in the third row of our chart.

$\begin{array}{c|c|c|c|}
& & \text{Unit} & \text{Total} \\
& \text{kg.} & \text{price} & \text{value} \\ \hline
\text{Fruit} & x & \3.75 & 3.75x \\
\text{Granola} & 30-x & \1.75 & 1.75(30-x) \\ \hline
\text{Mixture} & 30 & \2.75 & 82.50 \end{array}$

The third column gives us our equation:

. . $\text{(Total Value of Fruit) } + \text{ (Total Value of Granola)} \;=\;\text{(Total Value of Mixture)}$

Therefore, we have: . ${\color{blue}3.75x + 1.75(30-x) \;=\;82.50}$