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A study of a local high school tried to determine the mean number of text messages that each student sent per day. The study surveyed a random sample of 95 students in the high school and found a mean of 193 messages sent per day with a standard deviation of 68 messages. At the 
95% confidence level, find the margin of error for the mean, rounding to the nearest whole number. (Do not write 
+- ).
Answer:

A study of a local high school tried to determine the mean number of text messages that each student sent per day. The study surveyed a random sample of 9595 students in the high school and found a mean of 193193 messages sent per day with a standard deviation of 6868 messages. At the 95% 95 \% confidence level, find the margin of error for the mean, rounding to the nearest whole number. (Do not write ± \pm ).\newlineAnswer:

Full solution

Q. A study of a local high school tried to determine the mean number of text messages that each student sent per day. The study surveyed a random sample of 9595 students in the high school and found a mean of 193193 messages sent per day with a standard deviation of 6868 messages. At the 95% 95 \% confidence level, find the margin of error for the mean, rounding to the nearest whole number. (Do not write ± \pm ).\newlineAnswer:
  1. Define Margin of Error Formula: To find the margin of error at the 95%95\% confidence level, we need to use the formula for the margin of error (ME) in a sample mean, which is ME=z×(σ/n)ME = z \times (\sigma/\sqrt{n}), where zz is the z-score corresponding to the confidence level, σ\sigma is the standard deviation, and nn is the sample size.
  2. Find Z-Score for 9595% Confidence: First, we need to find the z-score that corresponds to the 95%95\% confidence level. For a 95%95\% confidence interval, the z-score is typically 1.961.96. This value can be found in standard z-score tables or by using a statistical calculator.
  3. Calculate Margin of Error: Next, we plug in the values into the margin of error formula. We have the standard deviation (σ\sigma) as 6868 messages and the sample size (nn) as 9595 students.\newlineME=1.96×(6895)ME = 1.96 \times (\frac{68}{\sqrt{95}})
  4. Calculate Square Root of Sample Size: Now, we calculate the denominator, which is the square root of the sample size nn.959.75\sqrt{95} \approx 9.75
  5. Divide Standard Deviation by Square Root: We then divide the standard deviation by the square root of the sample size. 689.756.974\frac{68}{9.75} \approx 6.974
  6. Multiply Result by Z-Score: Finally, we multiply this result by the z-score to find the margin of error.\newlineME=1.96×6.974ME = 1.96 \times 6.974\newlineME13.669ME \approx 13.669
  7. Round Margin of Error: Since we need to round to the nearest whole number, the margin of error rounded to the nearest whole number is 1414.

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