Question 1200458: Please help me with this probability question
The shelf life of a product has a mean, ū=10days and a standard deviation of 3 days. Assuming a normal distribution, determine the probability of a product lasting for
a) between 7 days and 13days
b) fewer than 7days
Thank you very much
Found 2 solutions by ikleyn, Theo:
Answer by ikleyn(52810)   (Show Source):
You can put this solution on YOUR website! .
Please help me with this probability question
The shelf life of a product has a mean, ū=10days and a standard deviation of 3 days.
Assuming a normal distribution, determine the probability of a product lasting for
a) between 7 days and 13days
b) fewer than 7days
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Using calculators like TI-83 or TI-84, call standard function normalcdf.
"normalcdf" stands for cumulative normal distribution function.
Its format is normalcdf(z1,z2,m,SD), where z1 and z2 are raw z-marks, m is the mean
and SD is the standard deviation.
For question (a), the probability is the area under the specified normal curve
between the raw marks 7 and 13
P = normalcdf(7, 13, 10, 3) = 0.6827. ANSWER
For question (b), the probability is the area under the specified normal curve
on the left of the raw mark 7
P = normalcdf(-9999, 7, 10, 3) = 0.1587. ANSWER
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.
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
Answer by Theo(13342)  (Show Source):
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