Question

100 points

Michael has $16 and wants to buy a mixture of cupcakes and fudge to feed at least 4 siblings. Each cupcake costs $4, and each piece of fudge costs $2.

This system of inequalities models the scenario:

4x + 2y ≤ 16
x + y ≥ 4

Part A: Describe the graph of the system, including shading and the types of lines graphed. Provide a description of the solution set. (4 points)

Part B: Is the point (2, 3) included in the solution area for the system? Justify your answer mathematically. (3 points)

Part C: Choose a different point in the solution set and interpret what it means in terms of the real-world context. (3 points)

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Answer 1

Explanation:

Part A:

The system of inequalities 4x + 2y ≤ 16 and x + y ≥ 4 can be graphed on a coordinate plane. To graph 4x + 2y ≤ 16, we can first graph the line 4x + 2y = 16. We can do this by finding the intercepts:

When x = 0, 4(0) + 2y = 16, so y = 8.

When y = 0, 4x + 2(0) = 16, so x = 4.

So, the intercepts are (0, 8) and (4, 0). We can connect these two points to graph the line.

To determine which side of the line to shade, we can test a point that is not on the line. For example, we can test the point (0, 0):

4(0) + 2(0) = 0 ≤ 16, so (0, 0) is in the shaded region.

Next, we can graph the line x + y = 4. This line passes through the points (0, 4) and (4, 0). To determine which side of the line to shade, we can test a point that is not on the line, such as (0, 0):

0 + 0 = 0 < 4, so (0, 0) is not in the shaded region. Therefore, we shade the region above the line.

The solution set for the system is the region that is shaded by both lines, which is the triangular region in the upper-left corner of the graph.

Part B:

To determine if the point (2, 3) is included in the solution area for the system, we can substitute x = 2 and y = 3 into both inequalities:

4(2) + 2(3) = 14 ≤ 16, so (2, 3) satisfies 4x + 2y ≤ 16.

2 + 3 = 5 ≥ 4, so (2, 3) satisfies x + y ≥ 4.

Therefore, the point (2, 3) is included in the solution area for the system.

Part C:

Let's choose the point (1, 3) as another point in the solution set. This means that Michael can buy 1 cupcake and 3 pieces of fudge, which would cost him:

1 cupcake * $4/cupcake + 3 pieces of fudge * $2/piece of fudge = $10

Since $10 is less than the $16 he has, he can afford to buy this combination of cupcakes and fudge. Therefore, the point (1, 3) represents a valid solution in which Michael buys 1 cupcake and 3 pieces of fudge to feed his siblings.