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]\[
\begin{aligned}
8^2 + 12^2 & = a^2 \\
64 + 24 & = d^2 \\
88 & = d^2
\end{aligned}
\][/tex]

A. She incorrectly calculated [tex]\( 8^2 \)[/tex].

B. She incorrectly calculated [tex]\( 12^2 \)[/tex].

C. She incorrectly added [tex]\( 64 \)[/tex] and [tex]\( 24 \)[/tex].

D. She incorrectly interpreted [tex]\( d \)[/tex] as [tex]\( a \)[/tex].

E. She should have multiplied the speeds by 1.5 hours before squaring them.



Answer :

Let's analyze the situation step by step:

1. Determine the distances traveled by Joseph and Isabelle after 1.5 hours:
- Joseph jogged north at 8 kilometers per hour.
[tex]\[ \text{Distance traveled by Joseph} = 8 \text{ km/h} \times 1.5 \text{ h} = 12 \text{ km} \][/tex]

- Isabelle rode her bike west at 12 kilometers per hour.
[tex]\[ \text{Distance traveled by Isabelle} = 12 \text{ km/h} \times 1.5 \text{ h} = 18 \text{ km} \][/tex]

2. Calculate the squared distances:
- The square of the distance traveled by Joseph:
[tex]\[ 12^2 = 144 \][/tex]

- The square of the distance traveled by Isabelle:
[tex]\[ 18^2 = 324 \][/tex]

3. Sum the squares of the distances:
[tex]\[ 144 + 324 = 468 \][/tex]

4. Using the Pythagorean theorem, find the distance [tex]\( d \)[/tex] between Joseph and Isabelle:
[tex]\[ d = \sqrt{468} \approx 21.63 \text{ km} \][/tex]

Now, let's check Omyra's calculations and identify her errors:

- Omyra's first step is correct:
[tex]\[ 8^2 + 12^2 = d^2 \][/tex]

- However, her calculation of the squares of the speeds was incorrect:
- [tex]\(8^2 = 64\)[/tex] is correct.
- [tex]\(12^2 = 144\)[/tex] is also correct, but she incorrectly added 24 instead of 144.

- Omyra incorrectly summed the squares as:
[tex]\[ 64 + 24 = 88 \][/tex]
Instead, it should be:
[tex]\[ 64 + 144 = 208 \][/tex]

- Since the square additions were incorrect, her conclusion [tex]\(d^2 = 88\)[/tex] is incorrect.

The correct statements describing her errors are:

- She calculated [tex]\(64 + 24\)[/tex] (which mistakenly assumes [tex]\(12^2 = 24\)[/tex]) instead of [tex]\(64 + 144\)[/tex].
- She concluded [tex]\(88 = d^2\)[/tex] instead of [tex]\(208 = d^2\)[/tex].

To summarize:

1. Omyra correctly identified [tex]\(8^2 + 12^2 = d^2\)[/tex].
2. She miscalculated [tex]\(12^2\)[/tex] leading to adding [tex]\(64 + 24\)[/tex] instead of [tex]\(64 + 144\)[/tex].
3. Her conclusion of [tex]\(88 = d^2\)[/tex] was based on incorrect arithmetic.

Her errors were in the calculation and summation of the squared distances.