Question 309134
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.
1st: find the mean of the sample = x-bar ; find the std = s
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2nd: find standard error = E = 1.96*s/sqrt(18)
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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?
n = [1.96*s/20]^2
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(c) Using Excel, plot a line chart of the data. What does the data suggest about the pattern over time?
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I'll leave that plotting to you.
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Cheers,
Stan H.
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