A recent study of the lifetimes of cell phones found the average is 24.3 months. the standard deviation is 2.6 months. if a company provides its 33 employees with a cell phone, find the probability that the mean lifetime of these phones will be less than 23.8. assume cell phone life is normally distributed variable.

Question

Mathematics

Sheldon Reese

25 November, 17:22

A recent study of the lifetimes of cell phones found the average is 24.3 months. the standard deviation is 2.6 months. if a company provides its 33 employees with a cell phone, find the probability that the mean lifetime of these phones will be less than 23.8. assume cell phone life is normally distributed variable.

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Nash Anderson · Answer 1

To answer this problem, we assume that the data is normally distributed so that we can use the z score. the formula for z score is

z = - (mean-data) / standard deviation

Substituting,

z = - (24.3-23.8) / 2.6 = - 0.1923

checking out from the z-table, probability is equal to 0.4247 or 42.47 percent.