People end up tossing 12% of what they buy at the grocery store (Reader's Digest, March 2009). Assume this is the true population proportion and that you plan to take a sample survey of 540 grocery shoppers to further investigate their behavior. Use z-table. a. Show the sampling distribution of (P), the proportion of groceries thrown out by your sample respondents (to 4 decimals). Can assume to be normally distributed because np>=5 and n(1-p)>=5 p = .12 standard error of the proportion o( p ) = b. What is the probability that your survey will provide a sample proportion within +.03 of the population proportion (to 4 decimals)?

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### Understanding Sampling Distributions

In a study published in *Reader's Digest* (March 2009), it was found that people tend to discard 12% of the groceries they purchase. Assuming this percentage represents the true population proportion, we aim to conduct a sample survey of 540 grocery shoppers to explore this behavior further. 

**a. Sampling Distribution**

To represent the sampling distribution of \(\bar{p}\), the proportion of groceries discarded by the surveyed sample, follow these steps:

1. **Assumptions**: We can assume the sampling distribution to be normally distributed if \( np \geq 5 \) and \( n(1-p) \geq 5 \).
   
2. **Proportion (p)**: Given as 0.12.

3. **Standard Error**: Calculate using the formula: 
   \[
   \sigma(\bar{p}) = \sqrt{\frac{p(1-p)}{n}}
   \]
   where \(\sigma(\bar{p})\) is the standard error of the proportion and \(n\) is the sample size.

**b. Probability Calculation for ±0.03**

Determine the probability that this survey will yield a sample proportion within ±0.03 of the true population proportion. Fill in the probability in four decimal places after calculation.

**c. Probability Calculation for ±0.015**

Calculate the probability that the survey will yield a sample proportion within ±0.015 of the population proportion:

- The probability is given as 0.7154.

Through understanding and calculating these values, researchers can estimate the accuracy and reliability of their findings regarding the proportion of groceries discarded by consumers.
Transcribed Image Text:### Understanding Sampling Distributions In a study published in *Reader's Digest* (March 2009), it was found that people tend to discard 12% of the groceries they purchase. Assuming this percentage represents the true population proportion, we aim to conduct a sample survey of 540 grocery shoppers to explore this behavior further. **a. Sampling Distribution** To represent the sampling distribution of \(\bar{p}\), the proportion of groceries discarded by the surveyed sample, follow these steps: 1. **Assumptions**: We can assume the sampling distribution to be normally distributed if \( np \geq 5 \) and \( n(1-p) \geq 5 \). 2. **Proportion (p)**: Given as 0.12. 3. **Standard Error**: Calculate using the formula: \[ \sigma(\bar{p}) = \sqrt{\frac{p(1-p)}{n}} \] where \(\sigma(\bar{p})\) is the standard error of the proportion and \(n\) is the sample size. **b. Probability Calculation for ±0.03** Determine the probability that this survey will yield a sample proportion within ±0.03 of the true population proportion. Fill in the probability in four decimal places after calculation. **c. Probability Calculation for ±0.015** Calculate the probability that the survey will yield a sample proportion within ±0.015 of the population proportion: - The probability is given as 0.7154. Through understanding and calculating these values, researchers can estimate the accuracy and reliability of their findings regarding the proportion of groceries discarded by consumers.
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