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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 199 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 199199 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 199199 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. Identify Given Information: Identify the given information.\newlineWe have a sample mean xˉ\bar{x} of 199199 messages, a standard deviation σ\sigma of 6868 messages, and a sample size nn of 9595 students. We want to calculate the margin of error at the 95%95\% confidence level.
  2. Determine Critical Value: Determine the critical value (z-score) for the 95%95\% confidence level.\newlineFor a 95%95\% confidence level, the z-score typically used is 1.961.96. This value is obtained from a standard normal distribution table or z-score table.
  3. Calculate SEM: Calculate the standard error of the mean (SEM). The standard error of the mean is calculated using the formula SEM=σnSEM = \frac{\sigma}{\sqrt{n}}, where σ\sigma is the standard deviation and nn is the sample size. SEM=6895SEM = \frac{68}{\sqrt{95}} SEM689.7468SEM \approx \frac{68}{9.7468} SEM6.976SEM \approx 6.976
  4. Calculate Margin of Error: Calculate the margin of error.\newlineThe margin of error (EE) is calculated using the formula E=z×SEME = z \times SEM, where zz is the z-score and SEMSEM is the standard error of the mean.\newlineE=1.96×6.976E = 1.96 \times 6.976\newlineE13.67296E \approx 13.67296
  5. Round Margin of Error: Round the margin of error to the nearest whole number.\newlineRounding 13.6729613.67296 to the nearest whole number gives us 1414.

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