A school administrator wants to see if there is a difference in the number of students per class for Portland Public School district (group 1) compared to the Beaverton School district (group 2). Assume the populations are normally distributed with unequal variances. A random sample of 27 Portland classes found a mean of 32 students per class with a standard deviation of 4. A random sample of 28 Beaverton classes found a mean of 33 students per class with a standard deviation of 3. Find a 95% confidence interval in the difference of the means. Use technology to find the critical value using df = 48.1993 and round answers to 4 decimal places. < μ1−μ2 <
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.
a. A school administrator wants to see if there is a difference in the number of students per class for Portland Public School district (group 1) compared to the Beaverton School district (group 2). Assume the populations are
Find a 95% confidence interval in the difference of the means. Use technology to find the critical value using df = 48.1993 and round answers to 4 decimal places.
< μ1−μ2 <
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