Data from the Bureau of Labor Statistics’ Consumer Expenditure Survey show that annual expenditures for cellular phone services per consumer unit increased from $235 in 2001 to $611 in 2007. Let the standard deviation of annual cellular expenditure be $42 in 2001 and $162 in 2007. What is the probability that the average annual expenditure of 136 cellular customers in 2001 exceeded $234? What is the probability that the average annual expenditure of 136 cellular customers in 2007 exceeded $577?
Inverse Normal Distribution
The method used for finding the corresponding z-critical value in a normal distribution using the known probability is said to be an inverse normal distribution. The inverse normal distribution is a continuous probability distribution with a family of two parameters.
Mean, Median, Mode
It is a descriptive summary of a data set. It can be defined by using some of the measures. The central tendencies do not provide information regarding individual data from the dataset. However, they give a summary of the data set. The central tendency or measure of central tendency is a central or typical value for a probability distribution.
Z-Scores
A z-score is a unit of measurement used in statistics to describe the position of a raw score in terms of its distance from the mean, measured with reference to standard deviation from the mean. Z-scores are useful in statistics because they allow comparison between two scores that belong to different normal distributions.
Data from the Bureau of Labor Statistics’ Consumer Expenditure Survey show that annual expenditures for cellular phone services per consumer unit increased from $235 in 2001 to $611 in 2007. Let the standard deviation of annual cellular expenditure be $42 in 2001 and $162 in 2007.
What is the
What is the probability that the average annual expenditure of 136 cellular customers in 2007 exceeded $577?
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