Question 207136: Dave the jogger runs the same route every day (about 2.2 miles). On 18 consecutive days, he recorded the number of steps using a pedometer. The results were:
3,450 3,363 3,228 3,360 3,304 3,407 3,324 3,365 3,290
3,289 3,346 3,252 3,237 3,210 3,140 3,220 3,103 3,129
(a) Construct a 95 percent confidence interval for the true mean number of steps Dave takes on his run.
(b) What sample size would be needed to obtain an error of ± 20 steps with 95 percent confidence?
(c) Using Excel, plot a line chart of the data. What does the data suggest about the pattern over time?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Dave the jogger runs the same route every day (about 2.2 miles). On 18 consecutive days, he recorded the number of steps using a pedometer. The results were:
3,450 3,363 3,228 3,360 3,304 3,407 3,324 3,365 3,290
3,289 3,346 3,252 3,237 3,210 3,140 3,220 3,103 3,129
1st: Find the mean (x-bar) and the standard deviation (s) of your data set.
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(a) Construct a 95 percent confidence interval for the true mean number of steps Dave takes on his run.
2nd Calculate the standard error:
E = 1.96*(s/sqrt(18)
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3rd:
95% CI: x-bar - E < u < x-bar + E
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(b) What sample size would be needed to obtain an error of ± 20 steps with 95 percent confidence?
Since E = 1.96[s/sqrt(n)], n = [1.96s/E]^2
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Cheers,
Stan H.
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