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.
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.
MATLAB: An Introduction with Applications
6th Edition
ISBN:9781119256830
Author:Amos Gilat
Publisher:Amos Gilat
Chapter1: Starting With Matlab
Section: Chapter Questions
Problem 1P
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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.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F010d10ea-7975-4510-a7a7-5e4f696daa17%2F968a60ff-12cc-4574-bc66-4d30b190c58b%2Fmv0r6z_processed.png&w=3840&q=75)
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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