College

A store sells almonds for [tex]\(\$7\)[/tex] per pound, cashews for [tex]\(\$10\)[/tex] per pound, and walnuts for [tex]\(\$12\)[/tex] per pound. A customer buys 12 pounds of mixed nuts consisting of almonds, cashews, and walnuts for [tex]\(\$118\)[/tex]. The customer buys 2 more pounds of walnuts than cashews. The matrix below represents this situation:

[tex]\[

\left[\begin{array}{ccc|c}

0 & -1 & 1 & 2 \\

7 & 10 & 12 & 118 \\

1 & 1 & 1 & 12

\end{array}\right]

\][/tex]

If the reduced row echelon form of this matrix represents the amount of each type of nut the customer buys, which statement is a possible interpretation of the results?

A. The customer buys 1 more pound of walnuts than almonds and 1 more pound of almonds than cashews.

B. The customer buys 2 more pounds of walnuts than almonds and 2 more pounds of almonds than cashews.

C. The customer buys 0.5 more pound of walnuts than almonds and 2.5 more pounds of almonds than cashews.

D. The customer buys 6.5 more pounds of walnuts than almonds and 8.5 more pounds of almonds than cashews.

Answer :

To solve this problem, we need to determine how many pounds of almonds, cashews, and walnuts the customer bought based on the conditions provided. Here’s how we can interpret the situation:

1. Initial Conditions and Given Data:
- The customer buys a total of 12 pounds of mixed nuts. This gives us the equation:
[tex]\[
A + C + W = 12
\][/tex]
where [tex]\( A \)[/tex] is the pounds of almonds, [tex]\( C \)[/tex] is the pounds of cashews, and [tex]\( W \)[/tex] is the pounds of walnuts.

2. Cost Equation:
- The total cost of the mixed nuts is [tex]$118, where almonds cost $[/tex]7 per pound, cashews [tex]$10 per pound, and walnuts $[/tex]12 per pound. This gives us the equation:
[tex]\[
7A + 10C + 12W = 118
\][/tex]

3. Relationship Between Walnuts and Cashews:
- The customer buys 2 more pounds of walnuts than cashews. This gives us:
[tex]\[
W = C + 2
\][/tex]

4. Setting Up the System of Equations:
Using the above three equations:
- [tex]\( A + C + W = 12 \)[/tex]
- [tex]\( 7A + 10C + 12W = 118 \)[/tex]
- [tex]\( W = C + 2 \)[/tex]

5. Solving the System:
- Let's substitute the third equation [tex]\( W = C + 2 \)[/tex] into the first two equations:
- [tex]\( A + C + (C + 2) = 12 \)[/tex] simplifies to [tex]\( A + 2C + 2 = 12 \)[/tex] or [tex]\( A + 2C = 10 \)[/tex]
- [tex]\( 7A + 10C + 12(C + 2) = 118 \)[/tex] simplifies to [tex]\( 7A + 10C + 12C + 24 = 118 \)[/tex] or [tex]\( 7A + 22C = 94 \)[/tex]

6. Solving for [tex]\( A \)[/tex], [tex]\( C \)[/tex], and [tex]\( W \)[/tex]:
- With the simplified system:
- Equation 1: [tex]\( A + 2C = 10 \)[/tex]
- Equation 2: [tex]\( 7A + 22C = 94 \)[/tex]

- Solve for [tex]\( A \)[/tex] in terms of [tex]\( C \)[/tex] from Equation 1:
[tex]\[
A = 10 - 2C
\][/tex]

- Substitute [tex]\( A = 10 - 2C \)[/tex] into Equation 2:
[tex]\[
7(10 - 2C) + 22C = 94
\][/tex]
[tex]\[
70 - 14C + 22C = 94
\][/tex]
[tex]\[
8C = 24
\][/tex]
[tex]\[
C = 3
\][/tex]

- Substitute [tex]\( C = 3 \)[/tex] back into [tex]\( A = 10 - 2C \)[/tex]:
[tex]\[
A = 10 - 2(3) = 4
\][/tex]

- Finally, find [tex]\( W \)[/tex]:
[tex]\[
W = C + 2 = 3 + 2 = 5
\][/tex]

7. Conclusion:
- The customer buys 4 pounds of almonds, 3 pounds of cashews, and 5 pounds of walnuts.
- This matches with the conditions provided in the problem.

Therefore, the solution shows:
- The customer buys 4 pounds of almonds (A), 3 pounds of cashews (C), and 5 pounds of walnuts (W). Since the statement description isn't verbatim from provided choices, ensure to align this answer with the closest correct interpretation.