A study was commissioned to find the mean weight of the residents in certain town. The study examined a random sample of 103 residents and found the mean weight to be 159 pounds with a standard deviation of 33 pounds. At the 95% confidence level, use the normal distribution/empirical rule to estimate the margin of error for the mean, rounding to the nearest tenth. (Do not write ± ).Answer:
Q. A study was commissioned to find the mean weight of the residents in certain town. The study examined a random sample of 103 residents and found the mean weight to be 159 pounds with a standard deviation of 33 pounds. At the 95% confidence level, use the normal distribution/empirical rule to estimate the margin of error for the mean, rounding to the nearest tenth. (Do not write ± ).Answer:
Identify Z-score for 95% Confidence: To calculate the margin of error at the 95% confidence level using the normal distribution, we need to use the formula for the margin of error (ME) which is:ME = Z×(σ/n)where Z is the Z-score corresponding to the desired confidence level, σ is the standard deviation, and n is the sample size.
Calculate Margin of Error Formula: First, we need to find the Z-score that corresponds to the 95% confidence level. For a normal distribution, the Z-score for a 95% confidence level is approximately 1.96. This value is obtained from a Z-table or standard normal distribution table.
Substitute Values into Formula: Next, we plug in the values into the margin of error formula:ME=1.96×(10333)
Calculate Square Root of Sample Size: Now, we calculate the square root of the sample size, which is 103. Using a calculator, we find that 103 is approximately 10.15.
Divide Standard Deviation by Square Root: We then divide the standard deviation by the square root of the sample size: 10.1533≈3.25
Multiply Result by Z-score: Finally, we multiply this result by the Z-score to find the margin of error:ME=1.96×3.25≈6.37
Round to Nearest Tenth: Since we need to round to the nearest tenth, the margin of error is approximately 6.4 pounds.
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