A triangular flag has a height of 15 inches and a base length of 25 inches. Magnolia makes a scale drawing of the flag in which the base length is 10 inches. What is the area of Magnolia’s scale drawing? Solve the problem by computing the actual area from the scale drawing. Show your work.(4 points)


Math Short Answer Rubric (4 points)
Points Awarded Criteria
4
The answer is clear and correct.

The answer shows that the student used problem-solving skills and reasoning.

All work is shown or explained.

3
The answer is mostly correct. The student made small errors while solving.

The answer shows that the student used some problem-solving skills and reasoning.

Most work is shown or explained.

2
The answer is partially correct. The student made errors while solving.

The answer shows that the student used some problem-solving skills or reasoning.

Some work is shown or explained.

1
The answer is incorrect. The student made errors while solving.

The answer shows little problem-solving skills or reasoning.

Little or no work is shown.

0 The question is not answered.


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1 answer

To find the area of Magnolia’s scale drawing of the triangular flag, we start by calculating the area of the actual flag, and then determine the area of the scale drawing based on the change in size.

  1. Calculate the area of the actual flag: The area \(A\) of a triangle can be calculated using the formula: \[ A = \frac{1}{2} \times \text{base} \times \text{height} \] For the actual flag:

    • Height = 15 inches
    • Base = 25 inches

    Plug in the values: \[ A = \frac{1}{2} \times 25 \times 15 \] \[ A = \frac{1}{2} \times 375 = 187.5 \text{ square inches} \]

  2. Determine the scale factor: The base of the actual flag is 25 inches and the base of the scale drawing is 10 inches. The scale factor \(S\) is: \[ S = \frac{\text{base of scale drawing}}{\text{base of actual flag}} = \frac{10}{25} = \frac{2}{5} \]

  3. Scaling down the area: When an object is scaled down, the area is affected by the square of the scale factor. Therefore, the area of the scale drawing \(A_{scale}\) can be calculated using: \[ A_{scale} = A \times S^2 \] Where \(S^2\) is: \[ S^2 = \left(\frac{2}{5}\right)^2 = \frac{4}{25} \]

    Now calculate the area of the scale drawing: \[ A_{scale} = 187.5 \times \frac{4}{25} \] \[ A_{scale} = 187.5 \times 0.16 = 30 \]

  4. Final answer: Therefore, the area of Magnolia’s scale drawing is: \[ \text{Area of Magnolia's scale drawing} = 30 \text{ square inches} \]

So, the answer is 30 square inches.