Question 1185533
the calculator at <a href = "https://davidmlane.com/hyperstat/z_table.html" target = "_blank">https://davidmlane.com/hyperstat/z_table.html</a> can help you find the answer to this.


mean = 48400
standard deviation = 5000


question 1:


If the manufacturer is willing to replace no more than 10% of the mobile phones, what should be the approximate number of hours for a warranty? Note: Express your answer in whole number.


the warranty should state that the approximate number of hours of life for the phone is guaranteed to be at least 41992.242


round to units to get 41992.


here are the results from the calculator.


<img src = "http://theo.x10hosting.com/2021/100911.jpg" >

question 2:


What is the probability that a mobile phone will last between 36,400 hours and 44,400 hours? Note: Express your answer in four decimal places.


the probability is equal to .2037


here are the results from the calculator.


<img src = "http://theo.x10hosting.com/2021/100908.jpg" >


question 3:


What is the probability that a mobile phone will last at least 55,900 hours? Note: Express your answer in four decimal places.


the probability is equal to .0668


here are the results from the calculator.


<img src = "http://theo.x10hosting.com/2021/100910.jpg" >


in question 1, you were looking for a value from an area.


in question 2 and 3, you were looking for an area from a value.


i confirmed with that the answers were consistent with the answers from my ti-84 plus scientific calculator.