Question 1175299: Margin of Error for Means
1.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 64 students in the high school and found a mean of 189 messages sent per day with a standard deviation of 80 messages. At the 95% confidence level, find the margin of error for the mean, rounding to the nearest whole number. (Do not write \pm±).
2.Confidence Intervals for Means
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 55 students in the high school and found a mean of 160 messages sent per day with a standard deviation of 85 messages. Determine a 95% confidence interval for the mean, rounding all values to the nearest whole number.
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! margin of error is t(0.975, df=63)*s/sqrt(n)
=1.998*80/8=19.98 or 20 messages
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half-interval is t(0.975,df=54)(*s/sqrt(n))
=2*85/sqrt(55)
=22.92 or 23
(137, 183) units messages
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