A statistics professor wanted to estimate the standard deviation for the grades that students received on his final exam. In a random sample of 30 of his previous students, he found that the standard deviation was 15 points. Construct and interpret a 90% confidence interval for the standard deviation for the grades on the professor's final exam. Note: The data is normal with no outliers. Round your answers to two decimal places. Edit View Insert Format Tools Table 12pt v Paragraph v I U Av ev T? v o v B.
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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