A government agency provides the number of miles that residents of the 75 largest metropolitan areas travel per day in a car. Suppose that for a simple random sample of 50 City A residents the mean is 22.6 miles a day and the standard deviation is 8.1 miles a day, and for an independent simple random sample of 40 City B residents the mean is 18.2 miles a day and the standard deviation is 7.1 miles a day. (a) What is the point estimate of the difference between the mean number of miles that City A residents travel per day and the mean number of miles that City B residents travel per day? (Use City A - City B.) mi/day (b) What is the 95% confidence interval for the difference between the two population means (in miles per day)? (Use City A - City B. Round your answers to one decimal place.) mi/day to | mi/day
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.
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