Previous 2 3 45 6 78 9 Next 6.3 Section Exercise 16 (calc) Question 7 of 9 (1 po

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Previous 2 3 45 6 78 9 Next 6.3 Section Exercise 16 (calc) Question 7 of 9 (1 point) A recent study of the lifetimes of cell phones found the average is 23.4 months. The standard deviation is 3.8 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 months. Assume cell phone life is a normally distributed variable, the sample is taken from a large population and the correction factor can be ignored. Use a graphing calculator and round the answer to four decimal places. Question Check Answer Solve It Guided Solution Link to Textbook Tables Formulas P (X

Explanation / Answer

here std error of mean =std deviation/(n)1/2 =3.8/(33)1/2 =0.6615

hence probability =P(X<23.8)=P(Z<0.6047)=0.7273

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