SOLUTION: *please help me solve this: Quality-control studies for Speedy Jet computer printers show that the lifetime of the printer follows a normal distribution with mean 4 years and stan

Question 1074392: *please help me solve this:
Quality-control studies for Speedy Jet computer printers show that the lifetime of the printer follows a normal distribution with mean 4 years and standard deviation 0.78 years. The company will replace any printer that fails during the guarantee period. How long should Speedy Jet printers be guaranteed if the company wishes to replace no more than 10% of the printers?
Z=_______
X=_______
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Quality-control studies for Speedy Jet computer printers show that the lifetime of the printer follows a normal distribution with mean 4 years and standard deviation 0.78 years. The company will replace any printer that fails during the guarantee period. How long should Speedy Jet printers be guaranteed if the company wishes to replace no more than 10% of the printers?
Find the z-value with a left tail of 10%
Z=invNorm(0.10) = -1.2816
-------------
Comment:: The time value you want is 1.2816 standard deviations
below the mean
X = -1.2816*0.78 + 4 = 3 years
-------------
Cheers,
Stan H.
-----------
RELATED QUESTIONS
Hi, I need help on the following stats problem... Thanks in advance. A computer store... (answered by stanbon)

Please help me solve this problem. A survey was made of the courses taken by 80 students (answered by richwmiller)

An internal control policy for an online fashion accessories store requires a quality... (answered by stanbon)

Can someone please help me solve this and explain why? Thank you The lifetime of a... (answered by stanbon)

Please help me solve this. An X-bar control chart monitors the mean of a process by... (answered by CPhill)

Anyone willing to help me with this problem? In a quality control inspection of sewing (answered by rfer)

Suppose a shipment of 140 electronic components contains 3 defective components. To... (answered by Edwin McCravy)

Anyone willing to help me please with this word problem? Thank you In a quality... (answered by sachi)

Here is the final question for the assignment. A quality control inspector samples... (answered by Edwin McCravy)