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:
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 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:
Identify Given Information: Identify the given information.We have a sample mean xˉ of 199 messages, a standard deviation σ of 68 messages, and a sample size n of 95 students. We want to calculate the margin of error at the 95% confidence level.
Determine Critical Value: Determine the critical value (z-score) for the 95% confidence level.For a 95% confidence level, the z-score typically used is 1.96. This value is obtained from a standard normal distribution table or z-score table.
Calculate SEM: Calculate the standard error of the mean (SEM). The standard error of the mean is calculated using the formula SEM=nσ, where σ is the standard deviation and n is the sample size. SEM=9568SEM≈9.746868SEM≈6.976
Calculate Margin of Error: Calculate the margin of error.The margin of error (E) is calculated using the formula E=z×SEM, where z is the z-score and SEM is the standard error of the mean.E=1.96×6.976E≈13.67296
Round Margin of Error: Round the margin of error to the nearest whole number.Rounding 13.67296 to the nearest whole number gives us 14.
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