问题


There is a single choice question about high school statistics. Answer the question by replying A, B, C or D.
Question: A student organization at a university is interested in estimating the proportion of students in favor of showing movies biweekly instead of monthly. How many students should be sampled to get a 90 percent confidence interval with a width of at most 0.08?
A. 27
B. 64
C. 106
D. 423
Answer:

答案

模型 模型答案 正确答案
金声玉亮2.0

To determine the required sample size for a confidence interval of a proportion, we can use the formula:

n = (Z^2 \* p \* (1-p)) / E^2

where:
- n = sample size
- Z = Z-score corresponding to the desired confidence level (for 90% confidence, Z = 1.645)
- p = estimated proportion (since we don't have a specific estimate, we'll use 0.5 as it gives the largest sample size)
- E = margin of error (half of the desired interval width, so for a width of 0.08, E = 0.04)

Plugging in the values:

n = (1.645^2 \* 0.5 \* (1-0.5)) / 0.04^2
n = (2.706 \* 0.25) / 0.0016
n = 0.6765 / 0.0016
n ≈ 423

Therefore, the correct answer is:

D. 423
D
deepseekr1

To determine the sample size needed for a 90% confidence interval with a width of at most 0.08, we use the formula for sample size in proportion estimation:
\[ n = \frac{Z^2 \cdot p(1-p)}{E^2} \]
- **Width** of the interval is 0.08, so the **margin of error (E)** is half the width: \( E = 0.04 \).
- For a **90% confidence level**, the critical Z-value is \( Z = 1.645 \).
- Since no prior estimate of the proportion (\( p \)) is provided, we use \( p = 0.5 \) (maximizing \( p(1-p) \)).

Plugging in the values:
1. \( Z^2 = (1.645)^2 \approx 2.706 \).
2. \( p(1-p) = 0.5 \cdot 0.5 = 0.25 \).
3. \( E^2 = (0.04)^2 = 0.0016 \).

\[ n = \frac{2.706 \cdot 0.25}{0.0016} = \frac{0.6765}{0.0016} \approx 422.8125 \]

Since the sample size must be an integer, we **round up** to **423**.

**Answer: D**
D
gpto1 D D
GPT-4o To determine the sample size needed to estimate the proportion with a specified confidence level and margin of error, we use the formula for the sample size of a proportion:

\[ n = \left( \frac{Z^2 \cdot p \cdot (1-p)}{E^2} \right) \]

where:
- \( Z \) is the Z-value corresponding to the desired confidence level
- \( p \) is the estimated proportion (if unknown, use 0.5 as it maximizes the sample size)
- \( E \) is the margin of error

For a 90% confidence level, the Z-value (from the Z-table) is approximately 1.645. The desired margin of error \( E \) is 0.08. Assuming no prior estimate for \( p \), we use 0.5 for \( p \).

Plugging in the values:

\[ n = \left( \frac{1.645^2 \cdot 0.5 \cdot (1-0.5)}{0.08^2} \right) \]

Calculating the numerator:

\[ 1.645^2 \approx 2.706 \]
\[ 0.5 \cdot 0.5 = 0.25 \]

So,

\[ 2.706 \cdot 0.25 = 0.6765 \]

Calculating the denominator:

\[ 0.08^2 = 0.0064 \]

Dividing the numerator by the denominator:

\[ n = \frac{0.6765}{0.0064} \approx 105.703125 \]

Since the sample size must be a whole number, we round up to the next whole number, which is 106.

Therefore, the number of students that should be sampled is:

\[ \boxed{106} \]

Correct answer: C. 106
D
llama3.1-70B-Instruct

C
D
llama3.1-405B-Instruct

D
D
DeepSeek-Coder-V2 C. 106 D
Qwen2-72B-Instruct D. 423 D
baichuan4 C D
doubao C

The formula for the sample size n is n = (z^2 * p * (1 - p)) / E^2. For a 90% confidence interval, the z-score is about 1.645. To find the minimum sample size, we assume p = 0.5 (maximum variance). E is the margin of error which is 0.08/2 = 0.04. Plugging these values in, we get n = (1.645^2 * 0.5 * 0.5) / 0.04^2 ≈ 106.
D
minimax To answer this question, we need to use the formula for the sample size of a proportion in a confidence interval:

\[ n = \left(\frac{Z^2 \cdot p \cdot (1-p)}{E^2}\right) \]

Where:
- \( n \) is the sample size,
- \( Z \) is the Z-score corresponding to the desired confidence level,
- \( p \) is the estimated proportion (since we don't have an estimate, we use 0.5 for maximum variability),
- \( E \) is the margin of error.

For a 90% confidence interval, the Z-score is approximately 1.645 (since the Z-score for 95% confidence is 1.96, and 90% is in the middle, we take the Z-score for 95% confidence).

The margin of error \( E \) is given as 0.08.

Since we don't have an estimate for the proportion, we use \( p = 0.5 \) to maximize the sample size (because \( p \cdot (1-p) \) is maximized when \( p = 0.5 \)).

Plugging in the values:

\[ n = \left(\frac{1.645^2 \cdot 0.5 \cdot (1-0.5)}{0.08^2}\right) \]
\[ n = \left(\frac{1.645^2 \cdot 0.25}{0.0064}\right) \]
\[ n = \left(\frac{2.707025 \cdot 0.25}{0.0064}\right) \]
\[ n = \left(\frac{0.***}{0.0064}\right) \]
\[ n = 105.743125 \]

Since we can't sample a fraction of a person, we round up to the nearest whole number.

The closest answer choice to 105.743125 is:

C. 106

So the answer is C. 106.
D
kimi To calculate the sample size needed for a given confidence interval, we can use the formula for the sample size of a proportion:

\[ n = \left(\frac{Z \cdot \sqrt{p \cdot (1-p)}}{E}\right)^2 \]

where:
- \( n \) is the sample size
- \( Z \) is the Z-score corresponding to the desired confidence level (for a 90% confidence level, \( Z = 1.645 \))
- \( p \) is the estimated proportion of the population (if unknown, use 0.5 for maximum sample size)
- \( E \) is the margin of error (in this case, 0.08)

Let's plug in the values:

\[ n = \left(\frac{1.645 \cdot \sqrt{0.5 \cdot (1-0.5)}}{0.08}\right)^2 \]

\[ n = \left(\frac{1.645 \cdot \sqrt{0.25}}{0.08}\right)^2 \]

\[ n = \left(\frac{1.645 \cdot 0.5}{0.08}\right)^2 \]

\[ n = \left(\frac{0.8225}{0.08}\right)^2 \]

\[ n = (10.28125)^2 \]

\[ n = 105.6289 \]

Since we can't have a fraction of a person, we round up to the nearest whole number, which gives us \( n = 106 \).

Answer: C. 106
D
wenxinyiyan C D
zhipu To determine the sample size needed for estimating a proportion with a specified confidence interval width, we use the formula for the sample size of a simple random sample:

\[ n = \left( \frac{Z_{\alpha/2}^2 \cdot p \cdot (1 - p)}{E^2} \right) \]

Where:
- \( n \) is the sample size.
- \( Z_{\alpha/2} \) is the critical value for the desired confidence level.
- \( p \) is the estimated proportion of the population (if unknown, 0.5 is often used because it maximizes the product \( p \cdot (1 - p) \)).
- \( E \) is the margin of error (half the width of the confidence interval).

For a 90% confidence level, the critical value \( Z_{\alpha/2} \) is approximately 1.645.

The width of the confidence interval is 0.08, so the margin of error \( E \) is 0.08 / 2 = 0.04.

Assuming no prior estimate for \( p \), we use \( p = 0.5 \) to maximize the product \( p \cdot (1 - p) \).

Plugging these values into the formula:

\[ n = \left( \frac{(1.645)^2 \cdot 0.5 \cdot 0.5}{(0.04)^2} \right) \]

\[ n = \left( \frac{2.706025 \cdot 0.25}{0.0016} \right) \]

\[ n = \left( \frac{0.67650625}{0.0016} \right) \]

\[ n \approx 423.129 \]

Since the sample size must be a whole number, we round up to the nearest whole number, which is 423.

Therefore, the correct answer is:

D. 423
D
gpto1 D D
deepseekv3 To determine the required sample size for estimating a proportion with a specified confidence interval width, we use the formula for the sample size of a proportion:

\[
n = \left( \frac{Z_{\alpha/2}}{E} \right)^2 \cdot p(1-p)
\]

Where:
- \(Z_{\alpha/2}\) is the critical value for the desired confidence level (90% confidence corresponds to \(Z_{\alpha/2} = 1.645\)),
- \(E\) is the margin of error (half the width of the confidence interval),
- \(p\) is the estimated proportion (if unknown, use \(p = 0.5\) for the most conservative estimate).

### Step 1: Calculate the margin of error (\(E\)):
The width of the confidence interval is given as 0.08, so the margin of error is half of that:

\[
E = \frac{0.08}{2} = 0.04
\]

### Step 2: Use the formula:
Since \(p\) is unknown, we use \(p = 0.5\) for the most conservative estimate:

\[
n = \left( \frac{1.645}{0.04} \right)^2 \cdot 0.5(1-0.5)
\]

\[
n = (41.125)^2 \cdot 0.25
\]

\[
n = 1691.015625 \cdot 0.25
\]

\[
n = 422.75390625
\]

### Step 3: Round up to the nearest whole number:
Since sample size must be an integer, we round up to 423.

### Final Answer:
**D. 423**
D