The lifetimes of the tread of a certain automobile tire are normally distributed with mean of 45,000 miles and a standard deviation of 3,000 miles. For each of the questions below make sure to show your work. Round any z-score calculated to two decimal places to find your result. What percent of tires have a tread life between 39,000 and 51,000 miles? The manufacturer wants to know what percent of times tread life is less than 37,500 miles. Find the tread life for the 90th percentile. Round to nearest integer (if needed)
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.
The lifetimes of the tread of a certain automobile tire are
For each of the questions below make sure to show your work. Round any z-score calculated to two decimal places to find your result.
-
What percent of tires have a tread life between 39,000 and 51,000 miles?
-
The manufacturer wants to know what percent of times tread life is less than 37,500 miles.
- Find the tread life for the 90th percentile. Round to nearest integer (if needed)
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