Nancy put new insulation in her attic and discovered that her heating bill for December decreased from $160 to $100. What is the
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Answer:
The sample size is
Step-by-step explanation:
From the question we are told that
The sample standard deviation is
The mean difference of the two groups is
The standard error is
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Let assume that the confidence level is 95% hence the level of significance is
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So the critical value of obtained from the normal distribution table is
Generally the margin of error is mathematically evaluated as
Generally the sample size is mathematically represented as
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