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 149 students in the high school and found a mean of 186 messages sent per day with a standard deviation of 99 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 149 students in the high school and found a mean of 186 messages sent per day with a standard deviation of 99 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 z-score: 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.
Calculate margin of error: 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 calculator that has the capability to calculate the inverse of the cumulative distribution function for the standard normal distribution.
Find square root: Next, we plug in the values into the margin of error formula: ME=1.96×(14999).
Divide standard deviation: Now, we calculate the square root of the sample size, 149, which is approximately 12.2066.
Multiply z-score: We then divide the standard deviation, 99, by the square root of the sample size, 12.2066, to get 99/12.2066≈8.1087.
Round to nearest whole: Finally, we multiply the z-score, 1.96, by the result from the previous step, 8.1087, to get the margin of error: 1.96×8.1087≈15.8931.
Round to nearest whole: Finally, we multiply the z-score, 1.96, by the result from the previous step, 8.1087, to get the margin of error: 1.96×8.1087≈15.8931.We round the margin of error to the nearest whole number, which gives us 16.
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