na survey, 33 people were asked how much they spent on their child's last birthday gift. The rest vere roughly bell-shaped with a mean of $40 and standard deviation of $3. alculate, state, and interpret a 95% confidence interval to estimate the mean amount of money arents spend on their child's birthday gift. Round to the nearest 100th where necessary.

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**Estimating the Mean Amount Spent on Child's Birthday Gift: Confidence Interval Calculation**

### Survey Information
In a recent survey, 33 individuals were asked about the amount of money they spent on their child's last birthday gift. The data collected exhibited a roughly bell-shaped distribution, characterized by the following statistics:
- **Mean:** $40
- **Standard Deviation:** $3

### Confidence Interval Calculation
To provide a reliable estimate of the average amount spent, we will calculate a 95% confidence interval for the mean amount parents spend on their child's birthday gift. We will round our answer to the nearest hundredth where necessary.

The formula for a confidence interval for a mean is given by:

\[ \text{CI} = \bar{x} \pm z \left( \frac{\sigma}{\sqrt{n}} \right) \]

where:
- \( \bar{x} \) is the sample mean
- \( z \) is the z-score corresponding to the desired confidence level (for 95%, \( z \approx 1.96 \))
- \( \sigma \) is the sample standard deviation
- \( n \) is the sample size
- \( \sqrt{n} \) is the square root of the sample size

Let’s plug in the values:
- \( \bar{x} = 40 \)
- \( \sigma = 3 \)
- \( n = 33 \)

First, calculate the standard error (SE):

\[ \text{SE} = \frac{3}{\sqrt{33}} \approx 0.52 \]

Next, determine the margin of error (ME):

\[ \text{ME} = 1.96 \times 0.52 \approx 1.02 \]

Finally, construct the confidence interval:

\[ \text{CI} = 40 \pm 1.02 \]
\[ \text{CI} = (38.98, 41.02) \]

### Interpretation
We can be 95% confident that the true mean amount of money spent on a child's birthday gift by the surveyed population falls between $38.98 and $41.02.

This calculation provides valuable insight for parents, retailers, and researchers into typical spending behaviors for children's birthday gifts.
Transcribed Image Text:**Estimating the Mean Amount Spent on Child's Birthday Gift: Confidence Interval Calculation** ### Survey Information In a recent survey, 33 individuals were asked about the amount of money they spent on their child's last birthday gift. The data collected exhibited a roughly bell-shaped distribution, characterized by the following statistics: - **Mean:** $40 - **Standard Deviation:** $3 ### Confidence Interval Calculation To provide a reliable estimate of the average amount spent, we will calculate a 95% confidence interval for the mean amount parents spend on their child's birthday gift. We will round our answer to the nearest hundredth where necessary. The formula for a confidence interval for a mean is given by: \[ \text{CI} = \bar{x} \pm z \left( \frac{\sigma}{\sqrt{n}} \right) \] where: - \( \bar{x} \) is the sample mean - \( z \) is the z-score corresponding to the desired confidence level (for 95%, \( z \approx 1.96 \)) - \( \sigma \) is the sample standard deviation - \( n \) is the sample size - \( \sqrt{n} \) is the square root of the sample size Let’s plug in the values: - \( \bar{x} = 40 \) - \( \sigma = 3 \) - \( n = 33 \) First, calculate the standard error (SE): \[ \text{SE} = \frac{3}{\sqrt{33}} \approx 0.52 \] Next, determine the margin of error (ME): \[ \text{ME} = 1.96 \times 0.52 \approx 1.02 \] Finally, construct the confidence interval: \[ \text{CI} = 40 \pm 1.02 \] \[ \text{CI} = (38.98, 41.02) \] ### Interpretation We can be 95% confident that the true mean amount of money spent on a child's birthday gift by the surveyed population falls between $38.98 and $41.02. This calculation provides valuable insight for parents, retailers, and researchers into typical spending behaviors for children's birthday gifts.
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