STATISTICAL TECHNIQUES AND TOOLS
CONFIDENCE INTERVALS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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We want to know if students work too much (and thus spend less time on their classes). Previous studies show that the standard deviation for work time is 3 hours, and a survey of 40 students has a mean of 9.8 work hours. The 95% confidence interval is ____
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(8.84, 10.76)
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(8.87, 10.73)
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(9.02, 10.58)
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(9.00, 10.60)
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Explanation:
Detailed explanation-1: -The general format of a confidence interval estimate of a population mean is: Sample mean ± Multiplier × Standard error of mean. For variable, a confidence interval estimate of its population mean is. x ¯ j ± Multiplier s j n.
Detailed explanation-2: –for confidence level 97% the Z Score is 2.17009; -for confidence level 98% the Z Score is 2.326; -for confidence level 99% the Z Score is 2.576; -for confidence level 99.99% the Z Score is 3.29053.
Detailed explanation-3: -A confidence interval for a population proportion is based on the fact that the sample proportions follow an approximately normal distribution when both n×p≥5 n × p ≥ 5 and n×(1−p)≥5 n × ( 1 − p ) ≥ 5 .
There is 1 question to complete.