As a result of tests on 15000 electric fans manufactured by a company, it was found that lifetime of the fans was normally distributed with an average life of 2050 hours and standard deviation of 60 hours. On the basis of the information, estimate the number of fans that is expected to run for i. More than 2140 hours and ii. Less than 1930 hours
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.
As a result of tests on 15000 electric fans manufactured by a company, it was found that lifetime of the fans was
i. More than 2140 hours and
ii. Less than 1930 hours
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