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:
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 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:
Define 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 confidence level, σ is the standard deviation, and n is the sample size.
Find Z-Score for 95% Confidence: 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 into the margin of error formula. We have the standard deviation (σ) as 68 messages and the sample size (n) as 95 students.ME=1.96×(9568)
Calculate Square Root of Sample Size: Now, we calculate the denominator, which is the square root of the sample size n.95≈9.75
Divide Standard Deviation by Square Root: We then divide the standard deviation by the square root of the sample size. 9.7568≈6.974
Multiply Result by Z-Score: Finally, we multiply this result by the z-score to find the margin of error.ME=1.96×6.974ME≈13.669
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 14.
More problems from Interpret confidence intervals for population means