On an electricity bill of $40.80, Mrs.
2 answers:
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Answer:
There is a 34.13% probability that the actual return will be between the mean and one standard deviation above the mean.
Step-by-step explanation:
This is problem is solving using the Z-score table.
The Z-score of a measure measures how many standard deviations above/below the mean is a measure. Each Z-score has a pvalue, that represents the percentile of a measure.
What is the probability that the actual return will be between the mean and one standard deviation above the mean?
One measure above the mean is
The mean is
This means that this probability is the pvalue of subtracted by the pvalue of
.
has a pvalue of 0.8413.
has a pvalue of 0.50.
This means that there is a 0.8413-0.50 = 0.3413 = 34.13% probability that the actual return will be between the mean and one standard deviation above the mean.