A study of a local high school tried to determine the mean amount of money that each student had saved. The study surveyed a random sample of 32 students in the high school and found a mean savings of 2900 dollars with a standard deviation of 1300 dollars. Use the normal distribution/empirical rule to estimate a 95% confidence interval for the mean, rounding all values to the nearest whole number.
Q. A study of a local high school tried to determine the mean amount of money that each student had saved. The study surveyed a random sample of 32 students in the high school and found a mean savings of 2900 dollars with a standard deviation of 1300 dollars. Use the normal distribution/empirical rule to estimate a 95% confidence interval for the mean, rounding all values to the nearest whole number.
Identify Mean, SD, Size: Identify the sample mean, standard deviation, and sample size.The sample mean (xˉ) is given as $2900, the standard deviation (s) is $1300, and the sample size (n) is 32 students.
Calculate SEM: Determine the standard error of the mean (SEM). The standard error of the mean is calculated using the formula SEM=ns. SEM=321300SEM=5.656851300 (rounded to five decimal places) SEM≈229.81 Round SEM to the nearest whole number: SEM≈230 dollars.
Find Z-Score: Find the z-score that corresponds to a 95% confidence level.For a 95% confidence interval, the z-score is typically 1.96 (this value comes from standard normal distribution tables).
Calculate Margin of Error: Calculate the margin of error (ME). The margin of error is found by multiplying the z-score by the standard error of the mean. ME=z×SEMME=1.96×230ME≈450.8 Round ME to the nearest whole number: ME≈451 dollars.
Calculate Confidence Interval: Calculate the lower and upper bounds of the 95% confidence interval.Lower bound = xˉ−MELower bound = 2900−451Lower bound = 2449 dollars.Upper bound = xˉ+MEUpper bound = 2900+451Upper bound = 3351 dollars.Round both values to the nearest whole number.
State Final Interval: State the final 95% confidence interval.The 95% confidence interval for the mean amount of money saved by each student is approximately $2449 to $3351.
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