Question 1203079: a manufacturer knows that their items have a normally dostributed lifespan with a mean of 10.2 years and a standard deviation of 2.9 years. if you randomly purchase one item what is the probability it will last longer than 5 years?
Answer by ikleyn(52781)   (Show Source):
You can put this solution on YOUR website! .
a manufacturer knows that their items have a normally distributed lifespan
with a mean of 10.2 years and a standard deviation of 2.9 years.
if you randomly purchase one item what is the probability it will last longer than 5 years?
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This probability is the area under the specified normal curve on the right
of the raw mark z= 5 years.
Use the standard function normalcdf (cumulative normal distribution function)
in your regular calculator TI-83 or TI-84
z1 z2 mean SD <<<---=== formatting pattern
P = normalcdf( 5, 9999, 10.2, 2.9).
It gives the ANSWER P = 0.9635 (rounded).
Solved.
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If you want to get better understanding, use online free of charge calculator
at web-site https://onlinestatbook.com/2/calculators/normal_dist.html
It has simple and intuitively clear interface.
In addition, it shows you a diagram with the area of interest shaded,
so at any time moment you do understand what you are doing
and what the calculator does for you, and why.
After playing with this online calculator, you will learn the subject enough.
After that, you may switch to ordinary calculator TI-83 or TI-84.
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If you need instructions on using function normalcdf in ordinary calculators, look at this link
https://www.usu.edu/math/cfairbourn/calculatorhelps/normalcdfti-84.pdf
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