A publishing company has just published a new college textbook. Before the company decides the price at which to sell this textbook, it wants to know the average price of all such textbooks in the market. The research department at the company took a sample of n=25 comparable textbooks and collected information on their prices. This information produced a mean price ?̅ of $145 for this sample. It is known that the standard deviation ? of the prices of all such textbooks is $35 and the population of such prices is normal. a) Construct a 90% confidence interval for the mean price of all such college textbooks. b) If you were to give a single number that estimates the mean price of all such college textbooks ?, what would that be?
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 publishing company has just published a new college textbook. Before the company decides the price at which to sell this textbook, it wants to know the average price of all such textbooks in the market. The research department at the company took a sample of n=25 comparable textbooks and collected information on their prices. This information produced a mean price ?̅ of $145 for this sample. It is known that the standard deviation ? of the prices of all such textbooks is $35 and the population of such prices is normal.
a) Construct a 90% confidence interval for the mean price of all such college textbooks.
b) If you were to give a single number that estimates the mean price of all such college textbooks ?, what would that be?
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