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 92 students in the high school and found a mean of 194 messages sent per day with a standard deviation of 63 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 92 students in the high school and found a mean of 194 messages sent per day with a standard deviation of 63 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 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 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 because it captures the central 95% of the normal distribution.
Calculate Margin of Error: Next, we will plug in the values for the standard deviation (σ=63 messages) and the sample size (n=92 students) into the margin of error formula.
Plug in Values: Now, we calculate the margin of error using the formula ME=z×(σ/n)=1.96×(63/92).
Calculate Square Root: We calculate the square root of the sample size, 92, which is approximately 9.5917.
Divide Standard Deviation: Now, we divide the standard deviation by the square root of the sample size: 9.591763≈6.5707.
Multiply Z-Score: Finally, we multiply the z-score by this result to find the margin of error: 1.96×6.5707≈12.8786.
Round to Nearest Whole: Since we need to round to the nearest whole number, the margin of error is approximately 13 messages.
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