Questions: A dairy needs 360 gallons of milk containing 7% butterfat. How many gallons each of milk containing 9% butterfat and milk containing 3% butterfat must be used to obtain the desired 360 gallons?
Transcript text: A dairy needs 360 gallons of milk containing $7 \%$ butterfat. How many gallons each of milk containing $9 \%$ butterfat and milk containing $3 \%$ butterfat must be used to obtain the desired 360 gallons?
Solution
Solution Steps
Step 1: Set up the equations
Given that we need \(T = 360\) gallons of milk with \(X = 7\%\) butterfat,
using milk types with \(Y = 9\%\) and \(Z = 3\%\) butterfat,
we set up two equations:
\(a + b = T\)
\(\dfrac{a \cdot Y + b \cdot Z}{T} = X\)
Step 2: Solve the equations
Substituting \(b = T - a\) into the second equation and solving for \(a\), we find:
\(\dfrac{a \cdot Y + (T-a) \cdot Z}{T} = X\)
Simplifying, we get \(a = \dfrac{T \cdot X - T \cdot Z}{Y - Z}\)
Plugging in the values, \(a = 240\) gallons.
Using \(b = T - a\), \(b = 120\) gallons.
Final Answer:
To achieve a final mixture of \(T = 360\) gallons with \(X = 7\%\) butterfat,
use \(a = 240\) gallons of milk with \(Y = 9\%\) butterfat,
and \(b = 120\) gallons of milk with \(Z = 3\%\) butterfat.