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Four different observers are standing in a straight line on a street and hear a siren from a police car. Each person recorded their observations in the chart shown.

\begin{tabular}{|l|l|}
\hline
\multicolumn{1}{|c|}{Siren Sound Waves} \\
\hline
Emilia & \begin{tabular}{l}
Information \\
fifteen seconds
\end{tabular} \\
\hline
Wycleff & \begin{tabular}{l}
heard a low-pitched sound the \\
entire time
\end{tabular} \\
\hline
Quincy & \begin{tabular}{l}
heard a high-pitched sound the \\
entire time
\end{tabular} \\
\hline
Lilly & \begin{tabular}{l}
noticed the Doppler effect at \\
three seconds
\end{tabular} \\
\hline
\end{tabular}

If the people are all lined up on the street at different blocks, and the police siren starts at block 3, which statement describes what block each person is standing at?

A. Wycleff is on block 1, Lilly is on block 4, Quincy is on block 12, and Emilia is on block 17.

B. Lilly is on block 1, Wycleff is on block 4, Quincy is on block 12, and Emilia is on block 17.

C. Lilly is on block 1, Wycleff is on block 4, Emilia is on block 12, and Quincy is on block 17.

D. Wycleff is on block 1, Lilly is on block 4, Emilia is on block 12, and Quincy is on block 17.



Answer :

GinnyAnswer
To determine the positions of the observers based on their observations of the siren sound waves, let's analyze each observer's report:

1. Quincy:
- Heard a high-pitched sound the entire time.
- This indicates that Quincy is closest to the source (block 3) as the siren moved towards him. Hence, Quincy must be at block 4.

2. Wycleff:
- Heard a low-pitched sound the entire time.
- This suggests Wycleff is farthest from the source (block 3) as the siren moved away from him. Hence, Wycleff must be at block 17.

3. Lilly:
- Noticed the Doppler effect at three seconds.
- The Doppler effect occurs when there is a noticeable change in the frequency of a wave in relation to the observer. This suggests that Lilly is at an intermediate distance where she can observe a change in pitch distinctly at some specific time. Hence, Lilly must be at block 12.

4. Emilia:
- Heard information about fifteen seconds.
- Since this number is intermediate compared to the high pitch and low pitch observations, it suggests another intermediate distance, but farther than the position where the Doppler effect was noted clearly. Hence, Emilia must be at block 1.

Putting this information together, we get:

- Wycleff is on block 17.
- Quincy is on block 4.
- Lilly is on block 12.
- Emilia is on block 1.

Thus, the correct statement is:

Wycleff is on block 1, Lilly is on block 4, Emilia is on block 12, and Quincy is on block 17.

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