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 61 students in the high school and found a mean of 176 messages sent per day with a standard deviation of 77 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 61 students in the high school and found a mean of 176 messages sent per day with a standard deviation of 77 messages. At the 95% confidence level, find the margin of error for the mean, rounding to the nearest whole number. (Do not write ± ).Answer:
Margin of Error Formula: To find the margin of error at the 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)where z is the z-score corresponding to the desired confidence level, σ is the standard deviation, and n is the sample size.
Find Z-Score: First, we need to find the z-score that corresponds to the 95% confidence level. For a 95% confidence interval, the z-score is typically 1.96. This value can be found in standard z-score tables or by using a statistical calculator.
Calculate Margin of Error: Next, we plug in the values we have into the margin of error formula:σ=77 messagesn=61 studentsz=1.96ME=1.96×(6177)
Calculate Denominator: Now we calculate the denominator of the margin of error formula: 61≈7.81
Divide Standard Deviation: We then divide the standard deviation by the square root of the sample size: 7.8177≈9.86
Final Margin of Error Calculation: Finally, we multiply this result by the z-score to find the margin of error:ME=1.96×9.86≈19.33Since we need to round to the nearest whole number, the margin of error is approximately 19.
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