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Joseph and Isabelle left Omyra's house at the same time. Joseph jogged north at 8 kilometers per hour, while Isabelle rode her bike west at 12 kilometers per hour. Omyra tried to figure out how far apart they were after 1.5 hours. Her work is shown below. Which statements describe her errors? Check all that apply.

[tex]\[ 8^2 + 12^2 = d^2 \][/tex]
[tex]\[ 64 + 24 = d^2 \][/tex]
[tex]\[ 88 = d^2 \][/tex]


Sagot :

Let's break down and analyze the problem step-by-step, identifying where Omyra made mistakes in her calculations:

1. Understanding the Movement of Joseph and Isabelle:

- Joseph jogs north at a speed of 8 kilometers per hour.
- Isabelle rides her bike west at a speed of 12 kilometers per hour.
- Both travel for 1.5 hours.

2. Calculating Distances Traveled:

- Joseph’s Distance:
[tex]\[ \text{Joseph's distance} = \text{speed} \times \text{time} = 8 \, \text{km/h} \times 1.5 \, \text{hours} = 12 \, \text{km} \][/tex]

- Isabelle’s Distance:
[tex]\[ \text{Isabelle's distance} = \text{speed} \times \text{time} = 12 \, \text{km/h} \times 1.5 \, \text{hours} = 18 \, \text{km} \][/tex]

3. Using the Pythagorean Theorem to Find the Distance Apart:

In this scenario, Joseph’s and Isabelle’s traveled paths form the two legs of a right triangle, with the distance apart being the hypotenuse [tex]\(d\)[/tex].

- According to the Pythagorean theorem:
[tex]\[ a^2 + b^2 = d^2 \][/tex]
where [tex]\(a = 12 \, \text{km}\)[/tex] and [tex]\(b = 18 \, \text{km}\)[/tex].

- Calculate:
[tex]\[ 12^2 + 18^2 = d^2 \][/tex]
[tex]\[ 144 + 324 = d^2 \][/tex]
[tex]\[ 468 = d^2 \][/tex]

- Solving for [tex]\(d\)[/tex]:
[tex]\[ d = \sqrt{468} \approx 21.633 \, \text{km} \][/tex]

4. Identifying Omyra's Mistakes:

In Omyra’s work:

- The equation she attempted to use was correctly set up initially:
[tex]\[ 8^2 + 12^2 = d^2 \][/tex]

- However, she made the following errors:
- Substitution Error:
In step [tex]$64 + 24 = d^2$[/tex], the correct summation should be:
[tex]\[ 8^2 + 12^2 = 64 + 144 = 208 \][/tex]
Therefore, the correct form should be:
[tex]\[ 64 + 144 = d^2 \][/tex]

- Calculation Error:
The statement [tex]$88 = a^2$[/tex] is incorrect because [tex]$64 + 24$[/tex] was mistakenly used instead of [tex]$64 + 144$[/tex]. Instead, it should be [tex]$208 = d^2$[/tex].

Based on the above analysis, the statements describing Omyra's errors are:

- [tex]$64 + 24 = d^2$[/tex]
- [tex]$88 = a^2$[/tex]

These statements indicate the calculation errors she made in the process.