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SolutionHW4

# SolutionHW4 - STAT500 HW#4_solutions STAT500 HW#4 Solutions...

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STAT500 HW#4_solutions STAT500 HW# 4 Solutions 1) a) 95% T Confidence Intervals Variable N Mean StDev SE Mean 95.0 % CI speed 20 9.100 2.573 0.575 (7.896, 10.304) b) The normal probability plot for reading speed suggests no reason to believe that the data aren’t normally distributed since the points all fall within the confidence limits. Speed Percent 18 16 14 12 10 8 6 4 2 0 99 95 90 80 70 60 50 40 30 20 10 5 1 Mean 9.1 StDev 2.573 N 20 AD 0.320 P-Value 0.508 Probability Plot of Speed Normal - 95% CI c) We are 95% confident, under repeated sampling, that the mean reading speed of all fourth-graders at the school is between 7.896 and 10.304 minutes. d) We are now 98% confident that the average reading speed is between 7.639 and 10.561 minutes for all fourth-graders at the school. The interval has widened with 98% confidence as compared to 95% (we have lost precision by demanding greater confidence for the interval). Variable N Mean StDev SE Mean 98.0 % CI Speed 20 9.100 2.573 0.575 (7.639,10.561) 1

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STAT500 HW#4_solutions 2) Apply normal probability plot to both ‘Before’ and ‘After’ data set since sample size is 10, less than 30. Before Percent 40 35 30 25 20 15 10 99 95 90 80 70 60 50 40 30 20 10 5 1 Mean 0.587 23.22 StDev 4.247 N 10 AD 0.272 P-Value Probability Plot of Before Normal - 95% CI After 40 35 30 25 20 15 10 99 95 90 80 70 60 50 40 30 20 10 5 1 Mean 0.899 25.33 StDev 4.249 N 10 AD 0.173 P-Value Probability Plot of After Normal - 95% CI
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SolutionHW4 - STAT500 HW#4_solutions STAT500 HW#4 Solutions...

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