In: Math
A saleswoman sells a? dried-fruit mixture for
?$5.90
per pound and nuts for
?$14.55
per pound. She wants to blend the two to get a
10?-lb
mixture that she will sell for
?$9.36
per pound. How much of each should she? use? Solve using matrices.
A saleswoman sells a? dry-fruit mixture for $ 5.90 per pound and nuts for
$14.55 per pound. She wants to blend the two to get a 10 lb
mixture that she will sell for $9.36
per pound. How much of each should she use? Solve using matrices.
Let the saleswoman use x lbs of the dry-fruit mixture and y lbs of nuts. Then x+y = 10…(1) and 5.90x +14.55y = 9.36(x+y) or, (9.36-5.90)x+ (9.36-14.55)y = 0 or, 3.36x – 5.19y = 0…(2).
The augmented matrix for this linear system is A =
1 |
1 |
10 |
3.36 |
-5.19 |
0 |
To solve this linear system of equations, we will reduce A to its RREF as under:
Add -84/25 times the 1st row to the 2nd row
Multiply the 2nd row by -20/171
Add -1 times the 2nd row to the 1st row
Then the RREF of A is
1 |
0 |
346/57 |
0 |
1 |
224/57 |
Hence, x = 346/57 = 6.07 and y = 224/57 = 3.93.
Thus, the saleswoman should use 6.07 lbs of the dry-fruit mixture and 3.93 lbs of nuts.