Dr. Higney, an academic researcher in an English department, wants to learn about the average length of a novel. In order to do this, Dr. Higney collects data on the word counts of 200 randomly selected novels. The sample mean of this data set is = 85252 with a sample standard deviation of 8413 words. Using this data, construct a 90% confidence interval for the true mean length of novels. (84,273.50, 86,230.51) (82719.67,89784.33) (94086.04, 96417.96) (80937.53, 90566.47)

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**Understanding Confidence Intervals in Novel Lengths**

Dr. Higney, an academic researcher in an English department, aims to study the average length of a novel. To achieve this, Dr. Higney collects data on the word counts of 200 randomly selected novels. Here's a summary of the data collected:

- **Sample Size (n):** 200 novels
- **Sample Mean (x̄):** 85,252 words
- **Sample Standard Deviation (s):** 8,413 words

**Task:**
Using this data, construct a 90% confidence interval for the true mean length of novels.

**Options for the 90% Confidence Interval:**

1. (84,273.50, 86,230.51)
2. (82,719.67, 89,784.33)
3. (94,086.04, 96,417.96)
4. (80,937.53, 90,566.47)

When constructing a confidence interval, it is essential to determine the range within which the true mean of the population is expected to fall, given a certain level of confidence (in this case, 90%).

To calculate the confidence interval, we use the formula:
\[ CI = x̄ \pm (z* \cdot \frac{s}{\sqrt{n}}) \]

Where:
- \( x̄ \) is the sample mean.
- \( z* \) is the z-value corresponding to the desired confidence level (for 90%, \( z* = 1.645 \)).
- \( s \) is the sample standard deviation.
- \( n \) is the sample size.

**Note:** The correct confidence interval should reflect these calculations.
Transcribed Image Text:**Understanding Confidence Intervals in Novel Lengths** Dr. Higney, an academic researcher in an English department, aims to study the average length of a novel. To achieve this, Dr. Higney collects data on the word counts of 200 randomly selected novels. Here's a summary of the data collected: - **Sample Size (n):** 200 novels - **Sample Mean (x̄):** 85,252 words - **Sample Standard Deviation (s):** 8,413 words **Task:** Using this data, construct a 90% confidence interval for the true mean length of novels. **Options for the 90% Confidence Interval:** 1. (84,273.50, 86,230.51) 2. (82,719.67, 89,784.33) 3. (94,086.04, 96,417.96) 4. (80,937.53, 90,566.47) When constructing a confidence interval, it is essential to determine the range within which the true mean of the population is expected to fall, given a certain level of confidence (in this case, 90%). To calculate the confidence interval, we use the formula: \[ CI = x̄ \pm (z* \cdot \frac{s}{\sqrt{n}}) \] Where: - \( x̄ \) is the sample mean. - \( z* \) is the z-value corresponding to the desired confidence level (for 90%, \( z* = 1.645 \)). - \( s \) is the sample standard deviation. - \( n \) is the sample size. **Note:** The correct confidence interval should reflect these calculations.
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